Plywood 15.5' Boat Construction Newbie needing help

Hello all,

I'm glad I found this site... I love using forums to get help for whatever project I want to take on... People are so helpful everytime.

Anyways,

So... I want to build a boat. A 14 or 15.5 foot Jon Boat. I've seen Uncle John's site and will probably go with their plans. I plan on modding it a lot though and putting in decking (with marine carpeting) and such for rodholders, stereo, etc...

I'm a complete newbie at this, but just really, really want to do it.

So some questions I have:
1.) How do I know how much epoxy/fiberglass cloth or tape I will need? I would like to fiberglass all of the joints, the bottom, and I dont know what else I'd have to glass over... Any help there is appreciated as well.

2.) I have installed cd players, and speakers and stuff in cars before... But have no clue where to start with a boat, especially since I'm building it all myself. How do I start the wiring process? If there are any easy-to-read tutorials about that, please point me to them... I need the wiring for my night lights on the boat and stuff as well.

3.) Any other tips anyone might have about building jon boats out of plywood, epoxy resin, and fiberglass cloth are greatly appreciated.

Again, I am thinking about a 48" bottom in width, and about a 14-15.5' length.

Of course I want a structurally sound boat, so I am willing to spend as much as I can within my budget (I am just going to be spending my spare money on supplies to build this all through the summer... I'm only a 22 year old college student, so I don't have a lot of money. Haha.)

-Uniquity

 

Uniquity,

Welcome aboard!

You've got a good start, working with recognized plans and a simple design as a first project. I'll let others with more building experience advise you on glassing in/over as you build it.

This is a good overview of boat wiring; just omit the stuff you don't need. Good advice on securing wiring and making good connections. Important even if you're not going 50+ mph. http://www.screamandfly.com/home/hull_tech/wiring_6.6.2004/wiring_1.htm

Google terms like: simple, boat, wiring, guide, etc. to find similar sites; do the same for terms like: install, marine, stereo, radio, etc. for your electrical equipment. Be sure the stuff is marine design; even the air around a boat is moist much of the time, and electrical devices don't like moisture very much.

Good luck with your build!

 

Yeah,

I'm pretty excited about it... I think this "hobby (I guess?)" is extremely interesting. It will be a nice summer project for me to keep my mind off of the stresses of college, among other things...

I have a question... Would "Uncle John's" jon boat design float as well as an aluminum boat?

I am interested in putting some carpeted decking in the boat and stuff as well, but I don't want to add too much weight. I am pretty new to this though, so maybe that wouldn't add too much. There would only ever be two people on it max, so about 350 lbs of passenger weight total. And probably just a decent trolling motor on the back (my lake isn't that large)...

Thanks for the link and tips... Very fast reply, as well.

Oh yeah, and I really want to add some sort of aluminum-pole supported little canopy to the backside... I can rig something like that up on my own though, I suppose.

-Uniquity

 

Carpeting is the quickest way to insure you'll have to pull it up and make repairs in the future.

On your first project, you should stick closely to the plans. As you mentioned, weight is a critical issue with small boats, one where excess can kill the performance pretty easily.

Uncle John's boat floats as described in the plans, but is more a function of how heavy you've built her and how much gear you've stowed aboard. She has plenty of reserve capacity.

Good luck and welcome aboard.

 

So what is a ballpark estimate on how much epoxy I would need to give it a couple of coats? I haven't the slightest idea, really.

 

The type of wood and quality of the wood/plywood used, environment, your expertise and the level of finish you desire all will dictate the amount of epoxy you'll need. I would think a minimum of 2 - 3 gallons will be necessary to tape all the seams, glue all the joints, apply a few coats to all the parts and sheath the bottom.

If you elect to sheath the boat, the weight and type of fabric you use will determine how much more you'll need, but plan on at least another gallon to sheath and fair the bottom and all the way up the sides. I recommend 3 coats of unthickened epoxy on all surfaces, including cutouts, notches, especially end grain and fastener holes, to be sure it's sealed. 2 coats will seal most of it, but some spots will be "dry" looking or not have a solid coating over it, which leads to problems down the road.

A 12 VDC trolling motor will yield about 3/4's of a horse power, which will push your boat to about 3 MPH (human walking speed), maybe slightly more, but not much. A small outboard (3 - 5 HP) will get you maybe to 6 - 7 MPH, but you'll be plowing a pretty big pile of water off the bow. With a 10 HP engine you'll likely get up on plane, in calm water, if the boat is trimmed properly, meaning you'll probably do around 15+ MPH. A 15 HP engine will be all you need for a small lake, pushing you along comfortably well into the 20's. You really don't want to over power this type of boat, though many do.

Buy the plans, absorb the information and check out their site. The plans should come with a full materials list and recommendations for epoxy and fabric.

Remember, you get what you pay for most of the time, so if these low priced plans seem to be lacking completeness and materials suggestions, then you know why.

 

I am currently building a 16 foot dory, glass over ply. For epoxy, a good rule of thumb is one ounce of resin per ounce of cloth weight, per yard. In other words, a 3 foot by 3 foot patch (1 yard) of 6 oz cloth needs about 6 oz of resin. One side of my dory was about 16 ft by 2 feet, so 16 x 2 = 32 sq ft, or about 3 ½ yards. I am using 6 oz cloth, so I needed about 21 ounces of resin. Figure about another 10 oz for the second coat. I am using Okume ply, which doesn’t drink too much resin, but you might need a little more for fir plywood.

Another unit of measure I had a lot of trouble finding was how much filler to buy for the coves. I used West Marine (expensive) products, and their cans of filler. I made about 32 feet of fillet with 64 oz of resin and 4 cans of colloidal filler. My fillets were too big though so you could probably get by with less. I’d strongly recommend limiting the size of your epoxy batches to about 16 ounces if the temp is over 75 degrees- I had a major screw up with a big batch.

Anyway, this will give you a rough idea of how much stuff you need. I have photographed most of the steps of my build at thehulltruth.com, photos section “building a stitch and glue dory”. Good luck, Chip.

 

all you really need to do with the fibreglass is just glass the chines and the keelson, just for extra support. so just times the length of the boat by three or howeva layers of glass u wana put on it. Always think 5 steps ahead before u fix anything, specialy the wires u dont wana glue a panel up and then not be able to hook all your electronics up,
good luck with your boat bro

 

hi, ply over glass boats r realli asy, and cheap. i'm 15, still in school and i have made 3 boats this year without a job...just £20 per month pocket money. alot of the things u need can be found. i buy ply good ply, but alot of the frames i make from scrap wood etc and refurb it. takes sum time but worth it. my first boat was a one sheet askiff by herb mcleod...free plans, resally easy and fun, till i put a big engine on it and nosedived into a huge wave. second was a jon boat, but i was majorly dissapointed . i expected it to be realli steady for fishin etc, but it is no better than a normal boat and is just bulky. if u want a good boat with cuddy/cabin that u can put a cd player in and big speakers, u should do something like the one i'm doing. its a hydroplane hull so the front cuts the water and then pushes it from th eback to give less friction (i think thats the theory) but the plans are free from svensons . com and r really easy to do. i will post pics tomorrow of my progress on the 3rd boat, i love it and it dusnt even float yet!

 

So I know this thread is about 2 years old now, haha...

But I actually started my boat last summer and am almost to the point of being ready to fiberglass and epoxy it now that it's warming up again.

It's a 15.5ft plywood jon boat, built somewhat in accordance to Uncle John's plans.

1. What kind of epoxy should I get? Does anyone have experience with Raka or AeroMarine? AeroMarine has a 3 gallon kit for $132.00, which seems pretty cheap to me. http://www.jgreer.com/

2. What weight and size of fiberglass cloth should I get? I plan on encasing the boat in fiberglass, so would it be in my best interest to get big sheets of it? Or should I just get a few rolls of the 3-4" tape and overlap it a bit all around? Is 6oz cloth the right weight for general boat building? Where is a good place to buy fiberglass cloth online?

I don't know anything about fiberglassing or epoxy. So any help is EXTREMELY appreciated. I worked hard to get my boat to the point that it's at now, so properly fiberglassing it is very important to me.

Thank you!

 

The cloth part is easy- use 6 oz fiberglass cloth. You don't need biaxial, or anything fancy.
I have only used West Marine resin, but for my next project I will try to find something cheaper. I think BoatUS sells system 3 for considerably less than West Marine stuff.
I don't think there is any difference in quality among the major brands.
FWIW, as you will soon find, its a lot easier and much less messy to apply cloth to the plywood before you put the boat together. When you apply the resin to a vertical (or near vertical) surface, runs and drips are inevitable.
A good method to appy resin is 'roll and tip'. Use a roller to apply resin quickly, then go over it with a brush to get a smoother surface. Works good for painting too. Good luck, Chip.

 

Wow. Hey, thanks for the great reply!

Yes, I have seen that a lot of people fiberglass before assembly. I wish I did already. Uncle John's should revise their boat plans to say that instead of coving all the edges and stuff afterwards.

For epoxy, I am going to give either US Composites or AeroMarine a shot.

And for fiberglass, I will probably just get the E-glass 6oz from US Composites.

One more question though, should I use 3-4" fiberglass tape over the whole thing and overlap the tape a bit (this is what Uncle John's plans told me to do)? Or should I buy big sheets of it and cut it to fit the areas correctly?

Are there any structural advantages to using bigger pieces of cloth than tape?