How thin is too thin?

[rschnack]

Hello again.<br /><br /> I have an 1969 16' Fiberglass Alumicraft boat I am starting to work on but I may stop. Through the advice in this forum I bought Jim Anderson's book "Runabout Restoration". I highly recommend this book to anyone who has any interest in old boats. Anyway, I followed his advise and surveyed my own boat. I noticed the fiberglass in the sides of the boat above the floor is not very thick, maybe 1/8". I can flex it a little by pushing on the side of the boat. Mr. Anderson recommends avoiding this type of boat since they are easily holed above the waterline. The boat also has verticle sides with a couple of 90 degree horizontal bends - also bad. My question is, were any of the boats of this vintage strong in this area? I thought the old boats had thicker glass than newer boats. Is the fiberglass this thin in new boats? Your thoughts would be appreciated.<br /><br />Best regards,<br />RCS

 

[NathanY]

Re: How thin is too thin?

If you are that concerned about it, add another coat of glass to it. It is not difficult, although it can be messy. The experience will be fulfilling and invaluable.

 

[DJ]

Re: How thin is too thin?

rschnack,<br /><br />I wouldn't be too worried about it. It's not going to be as strong as a premium boat. However, that all depends on what you're going to use it for.<br /><br />The 90 degree bends you speak of are, I believe, what is called lapstraking. That technique was more for style than anything else. It made glass boats resemble wood boats.

 

[mellowyellow]

Re: How thin is too thin?

my '72 16' seasprite hull weighs 1050lbs and is<br />rated up to 135hp!!! (bowrider)<br />a lot of that is extra thick glass. yes, thicker<br />glass was used 30 yrs ago., but each boat was<br />created separately... <br />that said, if'n the sides were that thin, I'd<br />look for a new boat.<br />my .02,<br />M.Y.

 

[JasonJ]

Re: How thin is too thin?

I wouldn't sweat it. If you think about it, that boat has made it up to this point just fine. Most boats are fairly thin on the sides. Common sense helps prevent most problems anyway. If you are the sort of person who runs into docks or plows through debris on the water, then an aluminum hull is the right answer. I had a 63 17 footer that you could actually see light through on the sides, but it was fine, even with the occasional dock bumping. The bottom is what needs to be strong. Good luck......

 

[magster65]

Re: How thin is too thin?

No worries, continue the resto.

 

[Jack Shellac]

Re: How thin is too thin?

Yeah, I remember some boats from this era that had the springy sides. You're right, though, that most of them were overbuilt because they didn't really know how strong fiberglas was at the time. Heck, it's made it for 34 years-- got to be something to it. I believe I'd go ahead.

 

[LOLHJ]

Re: How thin is too thin?

My starcraft has those thin sides, very thin. Never had any problems, although I really dont trust the gunnels that rest on those sides...<br /><br />Those sides rattle something wicked when under way as well.<br /><br />Oh well, im building my own boat from strach now...

 

[SCO]

Re: How thin is too thin?

I read that too in the book, but there is an advantage in weight savings, and the cg is lowered. My 73 glastron has flexible sides too,and probably 1/8 thk and I wondered if that was what the author was talking about. It hasn't proven to be a problem at all. You could walk around some new and used boatyards to get a feel for how they are typically constructed. You dont want to run into anything with the sides anyway. Even with beefy sides, impact with something will break up the glass, and a hole way above the waterline is not a big problem anyway.

 

[rschnack]

Re: How thin is too thin?

Thanks for the input. The lake I will use the boat in most of the time, Lake Charlevoix, can turn from smooth to white caps in the blink of an eye. This boat has been motoring around on this lake since it was new and seems no worse for the wear so I'll probably go for it. I have been keeping an eye open for a larger boat but the way the economy is going repairing this boat is probably the only way I can afford to get back on the water.<br />Thanks again,<br />RCS

 

[SCO]

Re: How thin is too thin?

Wouldnt be a bad idea to increase thickness where the sides meet the bottom of the hull. Then again, that can create an interface, where the thickened and thin meet, that flexes.

 

[cpasseno03]

Re: How thin is too thin?

I dont know if it helps any, but might be interesting. I had an old thunderbird 15 foot tri hull. The keel was pretty thick. the rest was very thin. Not quite a quarter of an inch. I would take it out in some crankin waves and after a while I noticed more water then usual in the bilge, I just thought that was from getting in and out for diving. So I put in a pump. still did it. Looked on the bottom and here is a big crack under the drivers seat runnning perpendicular to the keel. One foot long! Presumably just happened from the stress of runnin in waves. This was on the bottom and the boat was pretty well built square as a shoebox. But it was almost 1/4" thick... anyway thats my last experiance with "tupperware" boats steel or aluminum for me, thankyou!<br />Craig

 

[CalicoKid]

Re: How thin is too thin?

Fiberglass Alumacraft, huh? Funny. You think you've got thin sides? I have a canoe so thin you can see through it. Glass, even in thin layers, is very strong in combination with a good framework. Just be sure all the rest of the boat is sturdy and sound and that the fiberglass itself is not deteriorated in any way. If very thin fiberglass is damaged, it's difficult to mend and the damage can go farther than it would on a thicker piece. If your boat is solid, shine it up and get on the water!!