quick question about bondo

[inthegarage]

hi all, i have decided to build myself a boat. no mould just thin plywood covered in plexiglass. i have no idea what im doing but i like experimenting. i was wondering if anyone has ever used bondo over plexiglass on the exterior of their boat. im not sure what else is out there. any help would be appreciated. thanks

one more dumb question. is it a bad idea to put the gas tank in yhe front of the boat, because of all the bouncing

[Ike]

Bondo over glass on a new boat? Why? Bondo is occasionally used fair in damage on fiberglass boats but it's not a good solution. There are much better things on the market such as micro-ballons that do a much better job

Gas tank in the front? Not bad, but not good either, usually only done to balance the boat or if there is no where else to put it. Because of the acelerations involved tanks in the front have to be able to survive a tougher series of tests than tanks aft of the fore and aft mid point. Best place, mid point, out of the bilge so it won't get wet. The Coast Guard specifies the tests that tanks have to be able to survive and those that are forward have to be stronger. Tell the tank manufacturer you are planning on putting it in the bow and see what they say.

[inthegarage]

wow thanks for the responce as you can probably tell im new to all of this stuff. i thought bondo because im not sure how one of boats are created so smooth and perfect. what kind of fiberglass and resin do you suggest for strength and descent price that can be used to coat wood. see my plan here is to get the shape i want with 1/8 plywood and reinforce it with fiberglass on both sides. do yo think that will be strong enough for a 26 footer with a 350 chev. also generally how many layers of cloth or mat would normally be used. thankyou verry much for helping and any ideas would be greatly appreciated.

[Ike]

Fiberlass looks so shiny and smooth because it has a layer of gelcoat on the surface. But I'll let someone else talk about glass work because it's not my area of expertise. I have a general knowledge of it and have done a little fiberglass work but there are real experts here. In your case you would probably not have gelcoat on the surface because most boats are built in a mold and the gelcoat is applied as the first coat

[VKRUE]

INTHEGARAGE:

Please don't be offended... I think that your way off base.
1/8" plywood & bondo...26' long with a 350 chevy

If you are honestly serious, please indulge in some serious research about small, simple wooden boats before you hurt someone or yourself.

Might be safer for you to stick with the 350 chevy engine and buy some rails and wheels to put under it, maybe some No2 to boot

Seriously though, somebody / anybody please correct me if I'm out of place, I think that your way off base.

VKRUE

[hansp77]

In my limited experience, I would have to wholheartedly agree with VKRUE,
And please someone with real knowledge set us straight.
1/8 of an Inch?
Did I read that correctly?
Maybe 1/8 of a foot,
but with a 350 chevy? even that seems paltry.
that is bold to say the least...
(I can just see this engine pushing and ripping its way straight through the center of the boat to leave in its wake two sinking halves of the hull and one very dissapointed and wet Inthegarage!)

You would have to be laying on some very serious layers of fiberglass and cloth, as the strength gained from 1/8" would be practically nill in a boat that size.

Inthegarage, don't be put off your project, but you should read, read, read...
There are many posts and threads here already (overwhelming as it is to navigate at first) that would give you a much better understanding and starting point.

Hans.

[Hunter25]

Vkrue, you're dead on.

Designing a boat is not like building a mud bogger. If you fall out of a mud bogger, you land on the ground, maybe a little embarrassed. If your boat design is not stable and capsizes or sinks from unforeseen or planned reasons, you will have to be a real good swimmer. How good are the swimming skills of your friends and family?

Bondo will not stick to Plexiglas. Bondo will absorb moisture. Bondo will crack with vibration. All of these things can be found in a 350 powered boat built of door skin plywood and plexi. Plexi has no structural value at all.

1/4" plywood is way to thin. General scantlings for a power boat of those very general dimensions would have a 1/2" to 5/8" bottom with at least a 3/8" topside planking and a 1/2" deck. This would be skinned with a layer or two of 8 ounce fiberglass.

There is a reason people that design boats have an engineering degree. Do you?

Buy a tied old fiberglass hull that needs an engine and drop your 350 into it. They can be found every where. Of course you will need a drive unit, electrical system, plumbing system, steering system, engine operation controls and monitoring equipment. The list goes on and on, but you'll get a good idea. A 26' boat is a big hunk of boat, which will need a tandem axle trailer and a hefty car or truck to haul it around.

If bent on designing and building your own, then buy a small library of books on design and construction, then study like you're trying to get a degree.

I'm not trying to blow you of course, but it is not an easy task you have got planned. You can do it, but an education is very necessary, if you want to take your family out for an afternoon with having to explain why people had to swim home or worse.

[longliner45]

plenty of good kits around, by good boat designers for cheap! they have done all the research,,longliner

[inthegarage]

thanks everyone for your responses. i have no degree in engineering but i do have a big truck and trailer. i was under the impression that when moulding a boat, the hull was composed entirely of fiberglass. so why not make the shape of thin wood or whatever bends nice, and cover it with the same amount of fiberglass that would be used on a moulded hull. i dont take offence to any comments dont worry i know i have alot to learn. im just in planning stages and i will build my boat or at least start this year. i am the type who tries, fails, rips appart, gets hurt, tries again. i know the frame will need to be strong i just hope that someone can tell me if i use alot of fiberglass over thin wood will the fiberglass be strong enough. also how thick would the fiberglass have to be?, how many layers?, i checked out some places online for books and i will order one today, any suggestions on which one to get for my project. also whats the diffrence between biaxil, mat, cloth, thanks alot everyone

by the way the bondo idea was just to probe you guys for ideas on marine quality fillers and smoothers.

[Eagle Boats]

Another option that you may want to consider is to purchase a fiberglass hull and deck and finish off the boat yourself. What are you going to use the boat for? We have a mold to build a 26' sport fisherman hull, and two sets of 24 foot molds to build center consoles. Let me know if that is of interest to you.

[VKRUE]

Inthegarage:

Eagle Boats has an excellent suggestion there. Why not buy a fiberglass hull and finish the interior, engine, plumbing ect. yourself ???

There are always ads in our local shopper (classifieds paper) where you can buy a hull direct from the factory dirt cheap.

I'll find an ad and post the ad and / or the web address where you can see for your self.

i am the type who tries, fails, rips appart, gets hurt, tries again

Trying, failing, ripping apart and trying again are all good qualities of a determined person but, GETTING HURT doesn't fit. Personally, I don't think that there is any room for GETTING HURT in boat building / repairing. Someone getting hurt on my boat (when it is finished) is my worst nightmare.

Getting hurt away from shore, out on the water, at who knows what speed, could easily mean....................DEATH

And not necessarily you, but someone else in your boat or even another boat alltogether.....

Best of luck...

VKRUE

[marshmat]

Production fibreglass hulls are built in a mold, which has the smooth surface and the proper shape. The hull skin is laminated in the mold, the stringers and internal structure are added, and then the hull is pulled out of the mold for addition of deck and equipment. This procedure is not suitable for a one-off as the molds alone will be at least twice the cost of a good, fully finished production boat. The procedure also requires a LOT of experience to get it to work right.

The difficulty of engineering a vessel increases (take your pick, exponential or cubic) with length. People design and successful 13-footers all the time. Your 26-footer, though, is at least eight times the size and complexity of the common Sea-Flea. The calculations needed to design the structure are proportionally more numerous and more complex, and there is no simple answer to your questions. If you want to do your own design, you will need to find a naval architect to help you with it.

If you really want to build from scratch, I'd suggest you start with a stitch/glue or tack/tape hull in the 12-16' range. Full plans for good boats in this size can be had for $50. This will not be too expensive a boat and will give you a feel for the difficulties of fibreglass (it's really NOT FUN stuff, even at the best of times). Jumping right into a 26-footer will not be easy.

If you're after a fun project, that ends up with a good boat, try to find a solid bare hull of a suitable type. You can then design your own layout, rig your own engine, etc. without the expense and danger of starting a hull from scratch.

[inthegarage]

i appreciate yo
ur concern and suggestions. i am still planning exactly what i want to build. the stitch and glue technique seems to me like it can be built on a somewhat larger scale also. im going to build a 22-26 footer one way or another. i just need to learn more befori i start. when i siad "get hurt" i meant cuts or bruises. i have been building things all my life "im a tradesman" im sure a inferior structure would show itself long before hitting the water. but again i appreciate all the input.

i dont think i could start from a kit or moulded hull. to me whats the point, might as well just go buy a boat. something created by me from the ground up means to much.

i do now see that thin plywood is out of the question. i thought that fiberglass was normally laid on 1/2" thick. i guess wood structure is the norm.
any ideas on a good book for something like this. basically i want this baby to go fast. i have a 350 chev sitting in my shop great shape. a friend of mine says it dosent take much to convert this thing for a boat, not sure if i believe him. money isnt to big of a problem, i figure $15,000 max for motor, drive, glass, resin, plywood, tanks, electrical, plumbing, upholstery, and whatever else.

ps great forum and memers.

[VKRUE]

Hey, Inthegarage:

www.americanclassifieds.com

I have seen bare hulls ( 24' +) for sale more than once for less than $1000.00

Vkrue

[VKRUE]

Hey dude:

I know what you mean about something built by "ME".

I am very much the same way myself, which is why I'm restoring the 17' plywood boat that I bought 2 years ago. Is it worth the effort financially ? About $3000.00 so far and I project another 1 - 2 grand total to finish it the way I want to.

No............ but when it's done yea !!!!!!!

I'm not doing an "original" resotoration, but completely rebuilding this 46 year old wooden tub. Feel free to view my gallery pic's, have more to add soon too. I'm learning soooo much with this project and it's repairs and what not.

Anyway, when I'm done, I'll have a craft that I have literaly touched every single square inch of. I did all of the work. I made the decisions about what is what and how it goes.

Do you think that I might not appreciate this boat as much as if I built it from scratch? Not !

She's small & old but, she's mine.... all mine

VKRUE