homemade boat 5hp lawnmower engine(not complete)

[icedout]

Hello i am 16 years old .This summer 08 I began building this boat. Its 7 ft long 3.5 ft wide. I am using a push mower 5hp engine for the motor. When i first made the boat i used a belt drive system. At first the belt was to loose so when i created a belt tightener i ripped the belt all up. So then i went to an inboard outdrive. I origionally made homemade rc boats. Since this is my first time making a boat that i sit in i made the ratio 1:3 BIG MISTAKE! So now im done with the inboard outdrive im makeing a pure outboard now. Also i just began fiberglassing the boat. I put down a thin slab of bondo on the hull then put the fiberglass mat down. I press the mat down with a flat object so the bondo will get inbetween the fiberglass. After that i put a thick slab of bondo ontop.
What do you think?







Here is a awesome picture i got of lake erie
My main goal is to take the boat all the way around kellys island.

[thudpucker]

It looks like you've saved yourself enough money on boat construction to buy a Survival suit!

[icedout]

If you understand how a boat floats then you know if this boat will float or not...

[apex1]

Originally Posted by icedout

Hello i am 16 years old .This summer 08 I began building this boat. Its 7 ft long 3.5 ft wide. I am using a push mower 5hp engine for the motor. When i first made the boat i used a belt drive system. At first the belt was to loose so when i created a belt tightener i ripped the belt all up. So then i went to an inboard outdrive. I origionally made homemade rc boats. Since this is my first time making a boat that i sit in i made the ratio 1:3 BIG MISTAKE! So now im done with the inboard outdrive im makeing a pure outboard now. Also i just began fiberglassing the boat. I put down a thin slab of bondo on the hull then put the fiberglass mat down. I press the mat down with a flat object so the bondo will get inbetween the fiberglass. After that i put a thick slab of bondo ontop.
What do you think?



My main goal is to take the boat all the way around kellys island.
[/IMG]

Welcome here!
Thank you for showing us the result of your efforts.
Obviously everything is possible.............although I doubt that THIS will stay afloat long enough to take you round any island larger than itself.
I do´nt like to discourage you, I like your initiative, but to get this "boat" stiff and afloat in a proper manner you have to invest a lot of money and hassle.
Maybe the best advice is given by saying: search this Forum for a simple design that is within your budget and skills (apart from boldness it seems you have some), and invest in building a safe boat.

http://www.bateau.com/proddetail.php?prod=FL12 .................for example

If it comes to GRP works have a look here:
http://www.westsystem.com/ss/use-guides/
the job is almost the same in Polyester resin.

You may also google "stitch and glue boat" to get a clue how the others do such job.

Anyway, all the best and have success.

Regards
Richard

[icedout]

thanks ill make a post in about 3 moths here and let you know how this project turns out.

[apex1]

posted twice........ §<*#'&%

[TollyWally]

While there are certainly better ways to build a boat, congratulations on learning by doing. Your boat may or may not work, exercise caution before getting someplace you can't swim back from.

LOL the first boat I built sure wasn't anyuthing to write home about! If you stick with it some day in the not too distant future you'll build something to really be proud of. If you give it up in a short while at least you'll have some funny stories.

As you get older you will find out that a big part of growing up is all about the funny stories to tell when you get older! Good Luck.

[robherc]

Hmmm, like Apex said, BE CAREFUL & don't go anywhere you can't swim back from.

My guess it that your boat's chines (walls) will want to collapse in on you once it's carrying any ballast (you & the motor) in the water. Also, I hope you used something stronger than the foam I see to bond the sides to your framing. It might be a good idea to put a 1x4 across the middle to reinforce your walls; glue it to the middle of each of those two uprights I see. It'll be awkward to straddle when you're sitting in the boat, but the extra safety of having it hold the walls out will be worth it!

Also, I wouldn't want to hang that motor over the stern (back) of your boat for two reasons:

1. Your transom (back wall) won't be able to handle the weight of the motor hanging off of it & will most likely break.

2. The weight of the motor behind the boat will move your center of gravity too far aft (towards the back) & will make the back wall go down too far...water might come in.

So I'd recommend putting the motor just inside the back wall, and maybe doing an I/O drive there...to get the best balance on your boat & keep the water where it should be....outside!


Best of luck,
Rob

[mydauphin]

Please do not start a 5 hp motor attached to what is virtually a cardboard box. The torque of the motor will break something. And if the pulley or whatever doesn't break first something bigger might and a piece of flying metal may hurt you.

There are many safe ways to build a boat for no more than $100 and engines can be had used for $250. I have built many small boats like this. The only danger is not drowning.

[thudpucker]

I apologize for not seeing this sooner.
That motor you have is a Vertical Crank shaft motor.
It's not meant to run at an angle for very long.
You cannot lay it over to run that shaft at an 11 degree angle. The Carb wont work well and the Oil slinger in the engine wont pickup oil.

That photo is great. Makes a guy want to go out fishing. Maybe you should give up boat building and make some money at Photography?

[icedout]

Originally Posted by robherc

Hmmm, like Apex said, BE CAREFUL & don't go anywhere you can't swim back from.

My guess it that your boat's chines (walls) will want to collapse in on you once it's carrying any ballast (you & the motor) in the water. Also, I hope you used something stronger than the foam I see to bond the sides to your framing. It might be a good idea to put a 1x4 across the middle to reinforce your walls; glue it to the middle of each of those two uprights I see. It'll be awkward to straddle when you're sitting in the boat, but the extra safety of having it hold the walls out will be worth it!

Also, I wouldn't want to hang that motor over the stern (back) of your boat for two reasons:

1. Your transom (back wall) won't be able to handle the weight of the motor hanging off of it & will most likely break.

2. The weight of the motor behind the boat will move your center of gravity too far aft (towards the back) & will make the back wall go down too far...water might come in.

So I'd recommend putting the motor just inside the back wall, and maybe doing an I/O drive there...to get the best balance on your boat & keep the water where it should be....outside!


Best of luck,
Rob

Thanks for the information.lol that picture was just after the 3rd day of building it. I used 4 inch screws to hold the side of the boat walls to the main floor. Then i have 5 2x4 pieces of wood across holding them on also for extra support. You cant see that in that picture. Trust me im not making this thing out of wood glue and paper. I x2 reinforced everything on the final project.For the transom i took that wood out and used 3/4 pressboard wood. Not that junkey scraps of wood glued together. I forget the name of it. For the engine i got huge 3/4 inch diameter 5 inches long screws.

[icedout]

Originally Posted by thudpucker

I apologize for not seeing this sooner.
That motor you have is a Vertical Crank shaft motor.
It's not meant to run at an angle for very long.
You cannot lay it over to run that shaft at an 11 degree angle. The Carb wont work well and the Oil slinger in the engine wont pickup oil.

That photo is great. Makes a guy want to go out fishing. Maybe you should give up boat building and make some money at Photography?

Maybe i didnt give enough information on what im doing with the motor...
the motor is gonna be placed with the shaft vertically on the back of the boat. Like an outboard would look. Then a shaft is going to go down to that 90* gear box. So now the shaft is at a horizontal angle sticking out the gear box case underwater. On the vertical shaft going down into the gearbox casing im going to mount a air propeller to the vertical shaft so it will pressurize the gearbox case itself so no water will get in the casing while its underwater and the engine is going.

[robherc]

Hmmm...think you could put the engine & gearbox on the inside of the transom, then just run the prop shaft through a sealed bearing in the transom?
Your prop might be a bit higher & out of the clean flow underneath your hull, but you'd gain a lot in safety by not leveraging your transom down soo much, and by keeping your gearbox out of the water.

[icedout]

Originally what i did is you can see that hollow tube in on of the pictures. Well the shaft came out of there to the propeller. The hollow tube was higher than the water line so no water could get in the boat. The only proplem was when i did that inboard outdrive was the engine was having a hard time starting up at an angle.

If you all were interested the boat hold 410lbs before water will rush in.

[robherc]

410 lbs, not bad, how about with the motor mounted outboard?
Try testing it that way with about 150lbs in it...see how much freeboard you have left. Anything less than 8" freeboard and you'll be at a SERIOUS risk of having water come in the boat from waves out on the lake.

I'm not trying to tell you you can't do it, I'm just trying to help you avoid getting swamped on your maiden voyage