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Muskoka Seaflea => General => Topic started by: randyt on April 19, 2018, 12:23:38 AM

Title: Minimost XL modifications
Post by: randyt on April 19, 2018, 12:23:38 AM
A bit of a update on my Minimost XL project. Over my Xmas vacation back home I spent 9 of the 10 days in my buddies boat shop working on the 12 gallon under deck tank install as well as the transom modification for the Johnson 50 upgrade and a gauge package for the dash. I subbed out the upholstery job as I could not compete with the price and have no clue how to do that sort of thing. When I get back to the boat for my summer vacation we plan on a small lexan wind screen and a redo of the rear hatch cover and  painting the transom as the only remaining item on our to do list. I'm trying to post some photos of the work but for some reason I am not able to attach them at the moment. I'll keep working on it . Well the pics are starting to post but I have no idea why the first two are sideways . They wern't that way when i attached them LOL
Title: Re: Minimost XL modifications
Post by: seattle smitty on April 19, 2018, 04:49:41 PM
I particularly like the optimism indicated by your guage selection!!

Beautiful job, Roger!
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on April 19, 2018, 11:39:02 PM
This is Randy's boat, not mine.
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on April 19, 2018, 11:40:31 PM
So Randy, looks like as you ride around in your Minimost XL you will be very much in the lap of luxury.
Title: Re: Minimost XL modifications
Post by: 58 Johnson on April 20, 2018, 03:06:04 AM
I agree... that is some crazy good looking cockpit!  Congratulations.  Good on you. 
Title: Re: Minimost XL modifications
Post by: randyt on April 20, 2018, 03:20:03 AM
So Randy, looks like as you ride around in your Minimost XL you will be very much in the lap of luxury.

Well Its a upgrade from the original seats but a good bit. I never noticed until I started improving other aspects of the boat but I guess that is how these projects go , chasing away the weakest link :) Here is what they looked like before.
Title: Re: Minimost XL modifications
Post by: randyt on April 20, 2018, 03:24:48 AM
I particularly like the optimism indicated by your guage selection!!

Beautiful job, Roger!

I've always liked to know whats going on behind the scenes as it were and I have to admit the 160 mph speedometer is a bit optimistic but it will be fun to see the looks on little kids faces when they ask how fast it is . I am a fan of gauges I guess you could say as this is what my other toy looks like . I must have been a fighter pilot in a former life :)
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on April 20, 2018, 08:15:11 PM
Hey Randy, do you have a guage to keep track of your guages?
Title: Re: Minimost XL modifications
Post by: randyt on April 23, 2018, 08:50:59 AM
Hey Randy, do you have a guage to keep track of your guages?

I have them numbered and I have a guide taped to the dash :)
We used the car as a R&D mule for Mimi Cooper aftermarket parts and all those gauges come into play at different times . I just never bothered to take them out when we were done with that program .
Title: Re: Minimost XL modifications
Post by: seattle smitty on April 23, 2018, 04:31:52 PM
Roger, the next thing you'll see in Randy's (I say RANDY's) flea is a glass cockpit, plus he will have to have the helmet with the heads-up display, same deal in the Mini.

And maybe a wet bar?  Yeah, I can see Randy and Roger idling past each other out on the water at the next Fleafest in all their upholstered comfort, with one calling out, "Would you have any Gray-Poupon?," and the other replying, "But of course!"
Title: Re: Minimost XL modifications
Post by: 58 Johnson on April 24, 2018, 02:12:38 AM
... mais oui!!  Touché!!   :-D
Title: Re: Minimost XL modifications
Post by: randyt on April 24, 2018, 02:51:15 AM
Roger, the next thing you'll see in Randy's (I say RANDY's) flea is a glass cockpit, plus he will have to have the helmet with the heads-up display, same deal in the Mini.

And maybe a wet bar?  Yeah, I can see Randy and Roger idling past each other out on the water at the next Fleafest in all their upholstered comfort, with one calling out, "Would you have any Gray-Poupon?," and the other replying, "But of course!"

The heads up display is not a bad idea :) Actually the only add on left on the list is a small lexan wind screen to keep the water splashing on the deck from running back and landing in the laps of the riders.  After that is just going to be the tuning and set up process to get it to run as best it can. All part of the fun with our toys . The hard part for me is being 3500 miles away and other than the ten days over Xmas where we did the transom and tank mod I've had to supervise and research everything from afar . Out of curiosity does anyone have anyu idea when the Minimost XL plans were first published , even a ball park would be good to know ?
Title: Re: Minimost XL modifications
Post by: randyt on May 03, 2018, 03:19:09 AM
Well the paint modified transom is complete and has been painted as well as the hatch and the next stop is the outboard shop for a general spring tune up on the motor and we are getting close . I low lexan windscreen is most likely the last major item and after that it will be the test and tune process to get the boat to handle as best we can . That will take up a lot of my 8 week visit but I am looking forward to that part of the process .
Title: Re: Minimost XL modifications
Post by: randyt on May 08, 2018, 03:51:41 AM
Well today we finished up this round at the boat shop and its next stop is the engine specialist for a spring tune up and check over . There are a few minor things left to tackle but the big things on the check list are done .
Title: Re: Minimost XL modifications
Post by: seattle smitty on May 08, 2018, 05:08:56 PM
Anybody taking their engine in to a dealer for a tune-up/check-up should ask for the full-throttle rpm figure for it, as a target to shoot for when trying props.  Write down the lower unit gear ratio so you know what the propeller rpm should be.  See if they have a prop chart for the motor, listing the range of props covering both big, heavily-loaded boats and lightweight fleas.  Ask if there's a local prop expert.

And make sure they lube the lower unit.
Title: Re: Minimost XL modifications
Post by: randyt on May 09, 2018, 07:47:04 AM
Anybody taking their engine in to a dealer for a tune-up/check-up should ask for the full-throttle rpm figure for it, as a target to shoot for when trying props.  Write down the lower unit gear ratio so you know what the propeller rpm should be.  See if they have a prop chart for the motor, listing the range of props covering both big, heavily-loaded boats and lightweight fleas.  Ask if there's a local prop expert.

And make sure they lube the lower unit.

All good tips . I have the ratio, 2.41 and full throttle is 5400 from what i have read so far but will double check . I will see if he has a prop chart , the only one I found is rather generic for " normal " boats . Yes we have a prop tuner locally, https://www.halepropeller.com/ .  Chris rebuilt the lower unit for me , changed out the impeller all ready . the motor starts and runs but we are mostly looking for him to perhaps rebuild the carbs if needed and give it a good looking over . I was thinking of having him put in a more advanced reed system but we decided to get it running good in stock configuration for now and proceed with the boat tune before trying to improve the motor.

Thanks again for the tips, greatly appreciated.
Title: Re: Minimost XL modifications
Post by: Viky_CZ on May 09, 2018, 05:00:58 PM
Am I right to think that 2.41 ratio is way too slow for speedboat?
Title: Re: Minimost XL modifications
Post by: seattle smitty on May 09, 2018, 06:59:05 PM
Well, you are right in thinking that that is a lot of "underdrive" by speedboat standards. 2.41:1, meaning the crankshaft makes 2.41 revolutions for every one turn of the propshaft, IS quite a lot of under-drive for a little high-speed boat  .   .   .  which suggests that you need a prop with more pitch, maybe a lot more pitch, than the standard fishing propeller to make your little boats GO.  I raced with gear ratios like 12:15 underdrive, 16:21 underdrive, even 1:1 "direct drive."  And this was with crankshafts turning, depending on engine, peak revs anywhere from 7100rpm (stock racing Merc Mk20H)(avatar photo on left) to 10,000-some rpm (250cc Konig on methanol).  When you see gear figures like the 16:21 above, that meant the upper (driveshaft) bevel gear in the racing lower unit had 16 teeth and the lower (propshaft) bevel gear had 21 teeth, so if the crankshaft/driveshaft was turning exactly 7100rpm, the propeller shaft was turning 5408rpm.  The 1:1 ratio (which I also used on the boat at left) was with bevel gears that each had 14 teeth, IIRC) had the propshaft turning the same 7100 rpm as the engine, but with this ratio one used much smaller propellors, so the boat ran about the same speed.  The choice between the two ratios in this particular class usually hinged on what props you had.  If you had a really good 1:1 prop, and mediocre 16:21 props, well, you see the choice.  One more mile per hour was and is a big deal in Stock racing. 

I offer all this old racing lore just so you get a flavor of what gear ratios and prop choices can mean when you are working for the last little improvements.  This process is time-consuming and expensive, and certainly is not needed or even desirable with fleas. But it points in a general direction for making a boat work better.
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on May 09, 2018, 11:09:15 PM
I doubt there are any prop sellers in Southern Ontario who will let you try out a whole whack of their props and then let you pick the best one. Otherwise, one must buy the prop before they get to try it. Expensive indeed.
Title: Re: Minimost XL modifications
Post by: seattle smitty on May 10, 2018, 04:49:12 PM
So what you do, instead of just buying props on the chance they'll work, is first to write down your engine make, model, year, rpm and gear ratio, take a few photos of your boat out of the water with the engine hung on the transom, and email that to a good prop man like Ron Hill and ask him where to start. Tell him what you weigh, or at least guess at the anticipated load, and tell him the weight of the boat and the width of the bottom. He might have something that will work, or maybe he can suggest modifications to a prop you have.  Explain to him that you're not doing serious racing, and don't want to sink a bunch of money getting the last mile an hour.

Used props can sometimes be found gathering dust on marina shelves, or on Ebay or Craigslist, so you don't necessarily have to buy new.


We have something new to look forward to here shortly.  Randy, who has considerable experience in racing sail and knows the performance value of adding up incremental improvements arrived at with systematic testing (as opposed to seat-of-the-pants guessing), will be describing his boat-tuning sequence, I say his FULLY-INSTRUMENTED boat-tuning sequence, with comparative readings of ACTUAL rpm and mph with changes in motor set-up, props, and so on.
Title: Re: Minimost XL modifications
Post by: randyt on May 11, 2018, 05:03:34 AM
It will be a interesting experiment and I will have two months to get it sorted out and then my summer vacation is over . I will post what I can and will entertain all suggestions and comments . Smitty has given me some good guidance thru the building and modification phase so far and its been a big help . Approaching a good prop man once I have my facts straight is certainly on the list but I would like to see just how far off I am before I do that . Once I am in the water and get those base readings I will have a much clearer picture as to how to proceed or at least have more educated questions :) I received a few more photos today and its only making the wait harder .
Title: Re: Minimost XL modifications
Post by: randyt on May 31, 2018, 12:20:19 AM
Well after being connected to the project only by emails and sending checks for 8 months I finally am in CT with the boat and we are beginning our experimenting .

First day was just with the boat au natural, no trim appendages just to basic hull. The lake was calm , 90% full tank of fuel in the bow tank.

The boat got on a plane easily but did NOT like to go slow . It was porpoising quite badly in the slow to mid range stages . As we got into the higher RPM range about 4,000 the boat started to smooth off. All of this was with the motor in the fully trimmed in position . As we began to trim it out the boat freed up but it was a fine line and began to both bounce a bit and on the up move we could actually feel the rear start to come free of the water a bit so that was our limit, Speed was about 34 MPH with a max of 5100 RPM. This was with out 12 1/4 - 17 Michigan Wheel aluminum prop.  To be honest i was a bit concerned because I am actually planning on spending more time cruising than actual top speed runs . The steering was much improved over the previous motor , the Nissan 40 . I knew we had a long way to go but was happy with the apparent reliability of our refurbished motor. There is a slight chance that we are not getting full throttle out of it and will be having that looked into in the near future.  So the end result of day one was we feel very good about the hull strength wise and the modified transom was doubling as a nice water break as surprisingly enough we had NO water in the boat after a couple hrs on the water .

Day Two

Lake was calm, just under a half tank and Nauta smart tabs installed .

We took off with the tabs disengaged to get our selves re acquainted with the boat for one lap. I had purchased the optional bracket that allows me to just throw a lever and it lifts the tabs clear of the water which I wanted to be able to do with our testing and its a nice option if you are pulling up on a beach etc.

We engaged the tabs to their mid position and all I can say is that it is a different boat. Instead of taking a boat length and a half perhaps to get in plane, which is good obviously , its on plane in just about 10 ft which is of course better . The really big difference and one which gave me a good bit of relief as mid range speed was smooth and controllable down to 14 MPH . The steering was also improved a good deal . This boat really likes to lean into a turn and take a set as we say in the car world. I feel pretty good about the safety of a tight turn as the shape of the chines are at a angle which will be less apt to trip . When you press too hard peed the back end broke loose a little bit but it was quite controllable with good warning and feedback.  Top speed was about 36 at 5100 RPM.

Now for the confusing part . With the trim tabs the boat did not like any lift at all . The hop would begin almost as soon as you started to trim it out . The boat would of course begin to speed up but it would hop as well. I was not able to get anywhere like i did the first day when you could actually feel the back end break free just a bit. I've only seen two other Minimost XL's like mine and they both are run in a very negative trim position , is it possible that with the design of these hulls its just the way it is ? Of course with the hull making so much contact with the water its also a wet ride as well as slower than I think it could be .

One other difference between the days was that now we were down to a quarter tank of fuel so factor in perhaps 70 lbs less in the bow.  SO in one way I am going in the correct direction for getting the boat to cruise a bit but the fact I cant even begin to trim it out is a bit disappointing , I know the game is new but its still confusing.

Now our plan is to fill the tank and go back out again and see what we can get out of the trim tabs , Then we have another item to try,  the hydrafoil . I know that the trimming elements create drag but our hope was that we had enough power with the 50 to over come that and still get some speed out of it .

Anyway it has been a good week , when i got here the carbs were out for a rebuild and neither the boat nor trailer was registered and all that is done and we have a running boat . We plan on getting back out in a day or so and I will update accordingly .  Ive included a few pics . It is odd but if you youtube search MinimostXL they all have the same bow down attitude so it might just be what I will live with but i'm not giving up yet :)
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on May 31, 2018, 01:43:48 AM
For my comment I am assuming that when you say the boat had a "hop" you are referring to the boat porpoising. You need to move the centre of hydrodynamic lift further aft to get rid of the porpoising. It needs to be close to or behind the centre of gravity which is itself quite far aft in this boat. I think the easiest way to accomplish this is to make the trim tabs two or three times bigger. From the pictures it appears there is space to do this.

http://muskokaseaflea.ca/bb/index.php?topic=1629.msg10952#msg10952

All the best and have fun with your setting up!
Title: Re: Minimost XL modifications
Post by: randyt on May 31, 2018, 04:40:49 AM
Thanks for the comments. As the trim tabs are set in the middle posistion if I increase the leverage and make them “ work “ harder would that help move the lift you refer to rearward at all ?  Will the add of the additional fin the the antiventalation plate help in this regard in any way ?

Thanks again !
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on May 31, 2018, 02:40:44 PM
I thought already of the idea of trimming the trim tabs down (so they bite more). It would have some effect but with a drop in top speed. It's quite similar to having a hook in the keel, like the one quarter inch "monster" my boat, Suzie, has. Hooks are a problem because they cause the centre of hydrodynamic pressure to move fore and aft a lot as the angle attack of the boat changes.

I think it's much better to run the trim tabs flat, not biting. Making them bigger would bring the centre of lift aft where it needs to be.

Putting a large fin (like in the last picture you posted) on the antiventilation plate is probably going to be the best answer to your problem. You'll have to be sure to trim the motor correctly. Ideally, the fin should be coplanar with the bottom or possibly "kicked in" a little bit, but not too much. If you have power trim it's an easy adjustment to make. The large fin will lower top speed a bit but life is full of compromises. 
Title: Re: Minimost XL modifications
Post by: randyt on May 31, 2018, 02:52:46 PM
Thankfully we do have a nicely functioning power trim which is the reason we went up in size to this particular motor as the Nissan 40 that came with the boat did not have this option . We will be trying the large add on fin shortly and I will report our findings . As you say is all a trade off . More drag better ride perhaps but at a loss of top speed . I will keep the reports coming .
Title: Re: Minimost XL modifications
Post by: seattle smitty on May 31, 2018, 05:13:18 PM
Good report, Randy.  I'm guessing the whale-tail hung on the lower unit will work better than the tabs (subject to finding the right motor-height and angle).  Eager to hear about it.
Title: Re: Minimost XL modifications
Post by: randyt on June 11, 2018, 01:52:51 AM
Ok so the next installment on our set up process is complete.

We installed the Hydro fin and as I am becoming used to the results were good but not what i expected.

I was able to finally be able to use the trim again and the take off is almost laughable as there is almost zero bow lift, the boat just rises up a bit and then goes flat.

With the trim tabs in their least powerful mode the boat was able to achieve the same speed as without the fin as I was able to induce a few clicks of positive trim on the motor. We could get it to 35 nice and steady but with one more click it would hit 36 but the proposing would begin. Once click back down and it was steady again , that was its sweet spot. The RPMs were again at the 5000 mark. BTW according the the chart my desired rev range is from 4500 to 5500 RPM.

So the boat is steady , turns well and is controllable so I would say the basics are covered but now its the fine tuning we can play with .

We were able to get down to the 12 MPH range and still stay on plane which I was looking for which would be desirable for just cruising into a new area which was impossible before I started adding the trim items .

As an experiment we put the trim tabs in full attack mode and of course the boat got up on plane very well and amazingly enough we were still able to hit our 35 mph range . What was really nice was that I could get the boat to motor along at 5 mph with the bow down which was something I could not do before so I think that will also be useful in spots I am unfamiliar with.

Now for the negative of all this trim capability . We happened to come across a wake by surprise and buried our flat little platypus nose and shot a huge wall of water straight up into the air which we then passed thru and we did it to the second wave as well . Other than getting quite wet and the laughter subsided we decided we better work on some sort of evasive maneuvers for this type of situation .   Here is the rub. If , for example , we are moving along at 25 mph and spot a wake it takes us at least 15 seconds to slow down enough that the transom will sink a bit and the nose will come up . Between the " speed " of the trim and the natural slowing of the boat we cant seem to get into " safe mode " any quicker than that. We tried an abrupt pull back on the throttle , which is risky with a following wake but that didn't do anything at all . With all of our add ones to get the boat flat we can't get the nose up at all when we need to . Our only answer at the moment is to keep an eye peeled up far ahead and slow down far in advance of any trouble. We will work more on technique and see what other maneuvers we can try .

That is where we are at present and things are improving with each trip out. We noticed that our volt meter was pegged at 16 volts the time before and we replaced the regulator and all is good now with no more than 13 volts being recorded at any time.

I will keep posting when i have new info .

Randy
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on June 12, 2018, 02:03:44 PM
Nice going, it looks like you've got things set up pretty well now. I can't figure out how you might slow down quicker without defying the laws of physics unless you pioneer some sort of boat brake.

Maybe you could squeeze out more speed with a higher pitched prop? Possibly, but I have heard this rule of thumb: each inch of pitch lowers RPM by 2000. Even with your flat-bottomed beauty the rule probably applies to some extent.
Title: Re: Minimost XL modifications
Post by: seattle smitty on June 12, 2018, 05:50:09 PM
Quote from: randyt

Now for the negative of all this trim capability . We happened to come across a wake by surprise and buried our flat little platypus nose and shot a huge wall of water straight up into the air which we then passed thru and we did it to the second wave as well . Other than getting quite wet and the laughter subsided we decided we better work on some sort of evasive maneuvers for this type of situation .   Here is the rub. If , for example , we are moving along at 25 mph and spot a wake it takes us at least 15 seconds to slow down enough that the transom will sink a bit and the nose will come up . Between the " speed " of the trim and the natural slowing of the boat we cant seem to get into " safe mode " any quicker than that. We tried an abrupt pull back on the throttle , which is risky with a following wake but that didn't do anything at all . With all of our add ones to get the boat flat we can't get the nose up at all when we need to . Our only answer at the moment is to keep an eye peeled up far ahead and slow down far in advance of any trouble. We will work more on technique and see what other maneuvers we can try .    Randy

That seems odd. When you suddenly back the throttle down, the slow-turning prop should create a lot of drag.  It's like the prop is free-spinning or something (How? Impossible as far as I know.).  You say you can adjust the tabs so that you don't need the whale-tail?  Could the tabs be made operator-adjustable while underway?  And if so, would raising the tabs quickly at the same time you pull back the throttle tend to let the bow rise? I believe some of the Inboard racing runabouts have a foot-pedal that lets the driver adjust the big cavitation plate while at speed (probably with a rod that rotates a camshaft)(I haven't been to an Inboard race in a long time).

These accounts of your testing regime are very interesting, Randy.

FWIW, water-brakes on boats have been done, using a pneumatic cylinder that shoves a length of rod into the water, doesn't have to be very big, either, at higher speeds.  I think they powered these with something like a Freon cylinder (used for "air"-horns), and a spring retracted the rod. Such a brake could be made to slow the boat, though it would also have the unwanted (in this case) effect of pulling the bow downward.

I'm glad to hear the boat has shown enough recovery moment (plus all that weight on the transom) to bring the bow back up when you've dived into a roller.  Bad news if it keeps diving under!!

Roger, remember your rule of thumb on pitch goes out the window if you are willing to play with reducing blade area with the higher pitch props.
Title: Re: Minimost XL modifications
Post by: randyt on June 12, 2018, 10:53:20 PM
Nice going, it looks like you've got things set up pretty well now. I can't figure out how you might slow down quicker without defying the laws of physics unless you pioneer some sort of boat brake.

Maybe you could squeeze out more speed with a higher pitched prop? Possibly, but I have heard this rule of thumb: each inch of pitch lowers RPM by 2000. Even with your flat-bottomed beauty the rule probably applies to some extent.

The prop issue will be next on the list . I have already sent some info , specs and pics to Ron Hill to see if he has some thoughts . I was out today and getting the hang of it a little better . I was able to set a fairly nose high attitude which is how I would deal with any large wakes but I did have to be in slow mode to do it .
Thanks for checking in :)
Title: Re: Minimost XL modifications
Post by: randyt on June 12, 2018, 11:01:22 PM
The prop does not free wheel so that’s a non issue . Movable tabs would be nice but just out of the price range for something that will be a two month a year play toy . You are correct about the foot activated cavitation plate on the racing inboards . Actually most “flat bottoms “ have movable plates , I think it’s the only way they can get the damn things to turn :)

Interesting thing on water brakes . I was in a shop today and saw a jet ski with the advertising blurb of “first pwc with a brake “. I wasn’t able to figure out how it worked but I will be back there .

I also was very happy to see the nose come back up . In Cat sailing we call that “ going down the mine “ . The key is to keep that from happening in the first place . As I get better with the boat itself that should be less of a worry .

Thanks again for the comments .
Title: Re: Minimost XL modifications
Post by: randyt on July 08, 2018, 11:50:56 PM
Well we have had the boat out several times now and its proving to be just what we were looking for. The motor is reliable and the boat is water free , even as far as any spillage coming in over the transom on a quick stop. The additional  height we added to the transom does a great job of blocking the following wake mush more than we ever planned. I have a 1100 gph bilge pump back their waiting just in case but I think its going to last a long time based on usage :)
I am able to go as slow as i want for exploring and we even used it for a week at the shore towing a tube .  I was shocked at how level it was when even towing two adults. With the addition of the trim tabs the boat also turns much better than before and I am not even going to upgrade to the larger skeg I bought as the smaller water ski fin is doing the job nicely.

I would like to see some more top end out of it and that will be the next phase of development . I have basically one more week with it and then I am back in CA until December. We are still at the stage where I max out at 35 smoothly and when i trim up just a little more you can actually feel the boat break free of the water and start to accelerate but the porpoising starts at the same time.

Here are some photos of the boat actually in the water :)

We had built a dolly to bring the boat in and out of the water to deal with the low tide situation but found it to be a real pain in the ass. We made a rectangular frame out of 4 inch PVC and would put it under the boat and tie it to the hull and just let the tide go out and the boat would settle onto the sand but be suspended on the frame . The tide would return and the boat would float itself while tied bow and stern of course. Much easier :)
Title: Re: Minimost XL modifications
Post by: randyt on January 18, 2020, 07:22:16 AM
Well we had a productive summer with the little boat , made some additions and had a little bit of progress . We are happy with the results so far and it does everything i wanted it to do but knowing there is more to be had as far as the top end just makes me want to keep tweaking it . Last summer we added a very nice manual lift mount to the boat with a two inch set back. We raised the motor about 2 inches and were able to get a couple more mph out of t before the dreaded porpoise reared its ugly head . There is more to be had lift wise but we stopped at two for now . To be sure we were not running too high for the water pickup I utilized a little trick I saw at a hydro race and re routed the water exhaust port into the boat and thru the hull to my immediate right . I can actually see the stream as well as feel the heat with my hand to monitor the engine temp manually as it were.
To describe our limit i can best say that just when i hit that last little bit of trim in the up button at about 38 mph you can literally feel the boat free up from the water and start to surge ahead . Unfortunately  that is when the porpoising starts at about 40 mph. The feeling is that the boat starts to skip as the prop digs in , the bow raises , prop comes out of the water , nose comes down and then repeat . This is an exaggeration of the motions but that is what it feels like and i think you can see a bit of what i'm trying to explain in the videos i've added .  All speeds are recorded via GPS and my rpm is 5100 . The sweet spot for my 1994 Johnson 50 is about 5400 btw.
No someone gave me a interesting thought which i wanted to run by you all and see what you thought. He surmised that with the rear of the boat being completely flat that the drag at the stern might be one of my problems and perhaps a experiment might be in order . We all are aware of boats that run " on the pad " such as a Hydro Stream or Allison . His ideas was that if perhaps we could build into the bottom a small angled pad that the boat could get up on and free up some of that drag. Nothing like a deep V but just a gradual angles pad under the boat . We haven't talked about size or anything but perhaps something 18 or 24 inched wide at the stern and extending forward 24 inches or so with a total thickness of an inch or two at the rear. Its just an idea and would not be too hard to fabricate or install .
In any event we are having a ball with the boat and could leave it alone and be very happy but hot rodders whether on land or sea just have to tweak to be happy . I've messed with my road toy for 18 years now and still can think of things I want to do .
As usual i appreciate any input and I will be more active checking in with what is going on with you all .

https://youtu.be/UftPvxYacuA

https://youtu.be/eYH2mNHITbU
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on January 22, 2020, 04:13:47 PM
Looks like you've made a lot of progress with your boat!

If you installed a two foot wide angled pad at the transom it would definitely need to be functioning in opposition (force-wise) the the whale tail on the motor. Without the whale tail I think the angled pad wouldn't work at all because it would be like having a hook in the keel. With the whale tail trimmed right you could balance on it and on the the pad and the boat might ride like a v-bottom. You probably thought of this already but I thought I'd chime in anyhow.

Regards!   
Title: Re: Minimost XL modifications
Post by: randyt on January 23, 2020, 03:11:16 AM
Yes we were able to get quite a bit done and as I mentioned the boat is doing everything we want but were just looking for that little bit more. Your comments on the relationship between a added pad and the rear fin males a lot of sense . I am sure we will have a lot of experimenting to do with the various adjustments available to us . With the engine jack plate, adjustable smart tabs and the rear " dole " fin we should be able to make some changes , hopefully mostly good :) Thanks for your input and response .
Title: Re: Minimost XL modifications
Post by: randyt on January 23, 2020, 07:46:40 AM
Out of curiosity does anyone know when the Minimost XL was first designed ? people ask me about that some times and i just say sometime in the 50's but im just guessing .
Title: Re: Minimost XL modifications
Post by: 58 Johnson on January 23, 2020, 11:25:34 PM
Out of curiosity does anyone know when the Minimost XL was first designed ? people ask me about that some times and i just say sometime in the 50's but im just guessing .

Be sure to look around the MSF site.  There are lots of references and a couple of videos about the designer William Jackson.  The answer to your question is... “it depends”. 
Title: Re: Minimost XL modifications
Post by: randyt on January 24, 2020, 04:36:06 AM
I did delve into that quite a bit , even freezing some of the frame grabs in the video but the magazine article never showed the date . I think for the time being I wlll use " late 50's " until i find more definite info . 
Title: Re: Minimost XL modifications
Post by: jmuskoka on January 24, 2020, 03:44:00 PM
Hi Randy.....I am slowly getting things around here back on line and updated after a real crappy 2019!   January 18 2019  my retina blew up at the Toronto Boat Show and I am still having surgery....January 31 will mark the one year passing of my wife, October 15 saw my house burn down and on October 31 my insurance company decided to put a hold on my claim.  The good news is that 2020 is off to a WAY better start!    My very expensive lawyer is taking on my Insurance Company, my personal life is on an upswing and it's time to party!!!!!! 

So......here we GO!!!!!!!

Have you seen this?

https://www.youtube.com/watch?v=OJVsxMDBJV0

and yes.....I was the one who upscaled the Mini Most to the Mini Most XL......certainly not a big revelation in the boat design world, but the larger size seems to fill a need for many seaflea people!  Your own boat looks terrific!

Chris

Title: Re: Minimost XL modifications
Post by: randyt on January 24, 2020, 08:46:18 PM
So glad to see things have turned around . Having such a positive outlook on the future certainly pays credence to your personal strength and constitution.

I have watched the video you listed and found it quite interesting and he certainly was quite an interesting and accomplished individual . I kept trying to pick up and mention of the minimost design to get a “ birth date “. So based on your comments can it be said that the Minimost is a 50’s design with a redo by you in the early 70’s ? Your modifications to the original design certainly accomplished your goal of making the boat more versatile as I can take two adults for a spirited ride , tow a tube full of kids or adults or take a slow cruise up river . Thanks for your efforts !
Title: Re: Minimost XL modifications
Post by: randyt on January 28, 2020, 06:28:34 AM
Looks like you've made a lot of progress with your boat!

If you installed a two foot wide angled pad at the transom it would definitely need to be functioning in opposition (force-wise) the the whale tail on the motor. Without the whale tail I think the angled pad wouldn't work at all because it would be like having a hook in the keel. With the whale tail trimmed right you could balance on it and on the the pad and the boat might ride like a v-bottom. You probably thought of this already but I thought I'd chime in anyhow.

Regards!

I think you certainly see where we are trying to go with the pad experiment . The first question would be the size specifications for the pad itself . Think of it as basically a wedge shape .Would a gradual rise from zero to say 2 inches thick ( deep ) at the stern , perhaps 36 inches long and 12 to 18 inches wide make a difference ?  We don't want to make it too unstable , just free it up a little bit so we can take advantage of the extra power and not have to shut down at 40 mph when the porpoising starts in earnest. I would like to perhaps get as much as 10 more mph out of it if possible or anything close to that .   I'm sure it goes without saying it that we are totally novices when it comes to a boat like this and are just enjoying the process of trying to get what we can out of it . Thanks for the thoughts .
Title: Re: Minimost XL modifications
Post by: rogerduncan100 on January 28, 2020, 04:12:03 PM
Randy, take a look at this thread on V-bottoms. Maybe with the right shaped wedge you could turn your boat into one.

https://muskokaseaflea.ca/bb/index.php?topic=1623.msg10913#msg10913

Title: Re: Minimost XL modifications
Post by: randyt on January 30, 2020, 06:16:02 PM
That entire page was interesting, thank you .
Title: Re: Minimost XL modifications
Post by: randyt on February 07, 2020, 06:39:02 AM
Over this past short Xmas visit back to Ct we did a few improvements to the boat . We scrapped the original 1994 Johnson control cables that were 16 ft long for a pair of brand new 10' units . The improvement in the feel and movement of the of the levers was a noticeable improvement .
We also took three out of the four leafs in our trailer suspension out as it as originally designed for a 21 ft boat before we cut it down to our size . With the small amount of weight that our craft has compared to what it was designed for there was very little give over rough roads and the boat got bounced around a lot . With the one leaf it really does the job nicely .
The modification that i really was happy with was changing over to a smaller steering wheel. With the cramped quarters of the original 15 inch wheel sliding ones legs under the wheel and forward under the bow was a real squeeze . What most concerned me was that in the event of a needed quick escape from the boat or if there was a flip of some type having he lower body trapped under the wheel could lead to big problems . Its still tight , no doubt , but its a good deal better than before .
Looking forward to getting back out there in mid may and continue with the development .