MG20 questions befour start

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Matkuz
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MG20 questions befour start

Post by Matkuz »

Hello, after many questions i have decided to build MG as a bass boat. I need to say that BarraMan and his enthusiasm was very convincing :D After downloading plans i started to study and making 3D model of bass boat layout. So I have fiew questions.
I would like to downscale , 90%. After scaling down, volum of hull will be way smaller, so is it possible to still use 250 hp engine or it will be dangerous becaus of overweight ? I would like to use jackplate so the height of transom after down should not be problem, im i thinking good ?
If this is going to be a fishing machine, there should be a lot of storage, i would like to have big central rod locker under the front deck, and two smaller on right and left side. The D bulkhead is reduced to minimum and it is under the sole, how much of C and B can be cut out ? May by "entrance" in bulkhead C could by cut all the way up to make a notch.



fallguy1000
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Re: MG20 questions befour start

Post by fallguy1000 »

All designer questions.

why the sizedown?
My boat build is here -------->

viewtopic.php?f=12&t=62495

Matkuz
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Re: MG20 questions befour start

Post by Matkuz »

i need to size it down because when the boat will be under construction i can use whole of my garage space. But when it will come to winterize it i next years, i need space for boat and car.

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Re: MG20 questions befour start

Post by Jeff »

Do you mean scaling it down 10% and build it at 90% of the plans. Jeff

Matkuz
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Re: MG20 questions befour start

Post by Matkuz »

Yes, just like that.

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Re: MG20 questions befour start

Post by Jeff »

OK, just wait as the designer, Jacques Mertens-Goossens will respond soon. Jeff

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TomW1
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Re: MG20 questions befour start

Post by TomW1 »

If you downsize the boat, you need to downsize the motor, in this case to a 225HP motor. Remember when you downsize you do it in all directions. This will leave you with a boat that is only 6.3' wide and very skinny on the floor inside. Do make a model to see if it will fit your needs. The full-size MG would make a wonderful bass bpat I am not sure a downsized one will. But if you think it will build on, post pictures andj please ask ai many questions as you need to help get your MG built.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: MG20 questions befour start

Post by jacquesmm »

I agree with Tom but there is more. That 10% downsize will reduce the volume by 28%. The weight will not change much, same engine weight, same batteries and gear.. The cockpit will not be self bailing anymore or then, barely. You should raise the sole. That makes it less comfortable to sit but you don't really sit behind the wheel anyway.
For the frames, they must be at least 3" wide (75mm).

Scaling up is much easier than scaling down.
Jacques Mertens - Designer
http://boatbuildercentral.com

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BarraMan
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Re: MG20 questions befour start

Post by BarraMan »

As much as I luv the Mangusta hull, I decided to stay out of this conversation 8O ................... but then I got curious! :lol:

I have said before that it is easy to say, "I'll upscale by 10%", without fully appreciating the fact that that will turn a 'big' boat into a 'BIG'. I guess the reverse also applies!

Looking at my Mangusta plans, down-scaling by 10% will take the cockpit floor width from about 6' down to 5'6".
I have another boat! What we call a 'tinnie', ie pressed alloy, also in barra/bass boat configuration. We have chased barra for 20 yrs in this boat. Its 13' long and its cockpit width is 4', with front and rear casting decks. It has a 40 hp 4 stroke Yammie on the back and tops out at about 25 kts. We have comfortably fished 3 blokes casting lures - occasionally 4! 8O Three of us once spent the night in it - but that's another story! :D

So, after much thought, I think a 90% Mangusta hull could make quite a nice bass boat! I agree with Jacques that you would need to watch the weight, and if possible put the fuel tank(s) over the keel, under the sole, in order to get max stability at rest. You could get away with 2, maybe 3, batteries - depending on the trolling motor and electronics. Going lithium would be a big help if you have the $$.

I did a double-take at Tom's suggestion of 225 max hp! My 22 footer will hit 50 kts (58 mph) with its 250! :help: A 90% Mangusta hull would be a beast with 225 on the back - way overkill IMO, unless you want to run down lakes at 100 mph! 8O

Back in the day, I had a 17' ski boat with a 175 hp Merc 2 stroke on the back that would comfortable to do 60 mph. There is only about 70 lbs weight difference between a 175 and a 250, so not much weight saving to be made in the choice of motor. I think a 90% Mangusta hull would handle the 225 - you don't have to drive like a maniac! :lol:

In my experience, the bare hull is the cheapest part of a boat like that, so I built mine with the view that if it didnt work, I would burn it and build something else.

I look forward to seeing what you do. The world needs more Mangusta hulls! :lol:

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TomW1
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Re: MG20 questions befour start

Post by TomW1 »

Lee after reading your post I went back and checked my calculation. His max HP should be 200 that will give him a top speed of near or over 60mph. A 175 would put him in the 50's., more my speed. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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