SlinginINK

Hello,
I am new to this. I am very interested is running a gas boat this year. I have a few questions that some of you might be able to answer for me. I want to run a gas deep v with a weedwacker engine or similar type of motor.

Has anyone ever used or heared of using a husqvarna or stihl chainsaw motor in the 40-50cc range? I have several of these and wish to use them, they are very high RPM, (12,000)

What size of deep v (length) would I need for a motor that size?

Will I have a problem with finding a propeller for that type of motor?
Anything you see as a problem would be great.
Thanks

OLD_SLOW and in the WAY

Yeah man ! ! go for it.
there are some very nice drag hydro hulls about to hit the market. with the power of the saw engine a twin screw overdrive is very do able so you could spin two (normal) sized prop near 17,000 rpm. and with a good clutch set up you could do hole shots/wheelies..... or would it be a transomee
prop shop makes some 3 1/2" diameter 3 blades

SlinginINK

Thanks,

I really do not want to run a hydro as I am a little worried about the somewhat rough water I will be on and I will be using the boat mostly on a couple small rivers where I will not have very much room to turn around. So I think a deep v might be a better choice unless there is a design someone knows about.

The trouble I am running into is all of the hulls I have found online do not have a description of what motors to run in them. I do not have any problem with building a hull either.

magyarbacsi

Usually, guys get a hull and then look for a motor big enough to achieve their desired speed. Since you already have a monster motor, look for an off-shore model like in the 55-60" plus range for a 50cc. A boat that big may not be nimble enough to make your turns. I dont know what turning radius you are seeking. Check out the Mantaray, Apache, Popeye models for a starter, then ask the dealer the hull's limit for speed and power. Also a double rudder set up helps making sharp turns. Some dont like doubles, but I have several boats with them, and since I dont race or trying to set records, the extra drag is not a problem for me. The handling is superb and I can do 20' doughnuts at almost wot with my 48" deep v and a 230 motor. On a straight run, 45.8.

toyboy63

I f you are worried about fitting the engine in,when you buy the hull have them leave the stringers out.This way you can put them where you want.Most are wide enough.You may not be able to run with a hatch on.You would have to water cool it anyway.You might want to think about how you are going to hook a prop shaft to the engine.

SlinginINK

Hey thanks for all the info!
I must tell you that after looking at the messages you guys really know your stuff and are helpful. I hope that I can keep learning from here. I asked at the local hobbyshop for information about gas boats (big gas motors) and they had a blank stare.
A couple questions maybe you can answer;
1.Where can I look for information about connecting the clutch to a driveshaft (flexable or not)

2. Why do i need to watercool the motor? It isn't cooled on the saw. Could i just run the boat with a open hatch or some sort of cowl?

pompebled

Hi SlinginINK,

If building a hull is no problem, take a look in my gallery.
That's the 52 inch future housing for my 25cc Homelite, and, perhaps scaled up, will work fine with your 50cc Stihl, it's a Deep Vee, so choppy conditions are no problem.

Take a look at www.shark-racing.com how to watercool your engine (and much more info).

You can run the boat without the hatch, but watercooling is preferable.

In the US boaters make more use of a clutch than overhere it seems (less weight, less hustle, I think).
Make sure the flex shaft is designed to cope with the torque of your engine.

Greetings, Jan.

SlinginINK

Hey Thanks.

I looked at your gallery. That is just what I want to build! Where did you get the plans if you don't mind sharing the info?

It looks like you are well on your way to a nice boat!
Thanks again

skoda450

I was also new two years ago. Your chain saw engines will not convert to boats easily. The drive system is the problem. You need to connect to a flexable shaft or universal joint to accomodate the engine vibration/movement. Thats why weed whacker motors are popular. They use the same shaft to drive the trimmer end. Consider using one of them for your first boat and learn from from that to get to your more powerful chain saw engine. Good luck