Strange boat design?

[reelfishin]

I finally got a chance to get started replacing the transom in my 1962 Glaspar Tacoma, I cut away the inner transom and removed what was left of the old wood. The floor is rock solid with no rot. The only rotted wood was in the upper corners.
What shocked me the most was the lack of stringers? The floor sits only about 4 inched above the lowest point of the hull, it's made of 5/8" marine plywood with two layers of glass and resin on top. The entire hull is made of woven mat. I can see all the way up into the floor cavity and have cut open a bilge access point in the center about 8"x8". There are no stringers and no sign of any ever being there. There is barely enough room to get a hand into the center area below the floor. I know the floor in this was redone by a prior owner, and it's rock solid. the hull measures only 16' so there's not a lot of need for really super strong supports, but there are no lateral stringers at all, just the floor which contacts the inside of the outer hull nearly the whole way back other than about a 9" wide by maybe 2 in deep area right down the middle.
The boat had a 40 HP Merc on it, which I plan to reinstall, and ran and rode fine, I only cut into this since the upper 'wings' of the transom around the tie downs had gotten soft.
Were there many boats built this way? It's a closed bow, woven glass hull that is super light. The only wood I've found so far is the transom plywood, which is made up of several layers of thin plywood, the plywood inner wood on both gunwales and across the bottom of the dash.
It's the lightest boat of this type I've ever seen, two normal guys can carry the bare hull with ease. It ran like a speed boat with the 40 HP motor, yet I've seen these with up to 100HP on them. I've seen these badged as both Avalon and Tacoma models, with the only difference being seating layout.
How many boats didn't use any stringers?
(If this had stringers they'd have to have been nothing more than light wood strips) The current floor sits on the step in the hull that forms the outer chines.

 

[redfury]

Re: Strange boat design?

Well, shallow hulled aluminum boats and even my brothers 17ft Aluminum didn't use a stringer system, instead I've seen more of a "rib" style of support.

 

[oops!]

Re: Strange boat design?

hey reel...

thoes early boats.....some didnt have any strings......your talkin adout 62....if i rember my boat history...it was 59 when the first glass boat rolled into the new york boat show.....they were just learning back then.

they did have really solid hulls...they just kept throwing more glass on them....

you didnt say the length....what 14 ...16 feet?....and basically flat bottom ..right?

id say its fine....

cheers
oops

 

[reelfishin]

Re: Strange boat design?

The hull is 16' long, it's a V hull which flattens out at the rear to a slightly rounded bottom with two outer chines. The hull is real light, I can lift the the boat one end at a time on and off the trailer with very little effort. It's lighter than my 16' semi v jon boat. I would guess that the hull is under 500lbs, maybe even less. The outer hull is super thin, maybe an 1/8" or so. The now visible area under the floor shows no sign of any real support, just a flat floor laid across the bottom, sitting on the ledge formed on the inside by the lower corners of the hull. The floor contacts the bottom of the boat nearly the whole way across at the rear, I can't tell what it's like up front. The floor is rock solid with no give and the boat is very rigid with no noticeable twist if I lift one corner. It may have some sort of support farther forward, but it looks more like the floor is the main support or strength.
I bought this for it's trailer and really didn't plan on it being a fixable boat, but it turned out to be pretty decent, and I liked how light it is. It should be pretty easy on fuel when I'm all done.
My only real concern is the strength of the transom. Its a curved design with very little other support. The original transom wasn't super tight to the bottom of the boat, it was sort of straight cut and only went about a 1/2" below the floor edge in the center. The floor was replaced at some point, the former owner told me he paid some marina to redo it. The floor replacement job looks super professional and I suppose the may have lowered the floor a bit. The boat appears to have been built without any access to the bilge originally, it has two drain plugs, one below the floor level that allows you to drain the sealed area below the floor, and one above the floor on the far right side. Both are tiny 5/8" drain plugs.

It don't really seem to need any forward support, and most likely won't see more than a 40 or 50 hp motor. I will add a forward gusset to the middle of the transom and I will build a functional splash well. It only has a shallow fiberglass pan that bolts to the front of the transom now which gives no real added support. The scary part is that I've seen these hulls with early 100hp v4's on them. The transom will be far stronger once I'm done than what it ever was, the original was just 4 layers of 3/8" plywood all ran with the outer grain vertical. Most of the wood I took out was intact, there was about 8" rotted on each corner from upper gunwale run off into the transom cavity.
This will all now be sealed.

My plan is to use 6 layers of 1/4" plywood with each one changing direction. I'll have to laminate each one in place at a time from the inside. I do not want to cut or damage the other transom glass at all. The original wood was no laminated in any way, it came out in 4 separate pieces. Another thing that surprised me was how smooth the inner side of the rear transom fiberglass is. It's gel coated just like the outside, smooth and shiny. It's very thin, no heavier than the rest of the hull.

The inner wall of the transom was only paper thin, I cut it away with a utility knife. The fibers are very short, but the overall appearance of the mat they used looks woven. When I cut into the original glass the fibers are bright yellow in color. The fibers are more like dust than long fibers. It looks more like modern carbon fiber when cut. I am using epoxy for the rebuild, I can't say what type of resin they may have used. However, what ever they used when they did the floor is certainly well adhered to the sides. The resin and glass they used on the floor are far harder than the original glass or resin.

I wish that I lived in a state with better freshwater boating areas, this would be a perfect big lake boat when its done. Around here I'll only be able to run it in a the upper river and maybe a few back bays. Its not big enough or stout enough to go into any bigger waters, but would be really cool on a large lake.
My goal is to make pretty much an open fishing boat out of this, the last owner even glassed in stainless studs for two seat pedestals. It will have to forward swivel seats and the rest of the rear will be wide open. The under bow area will be finished off a bit and I was considering a permanent forward fuel tank up there as well to lighten the rear of the boat a bit. The way it was set up before it had two 6 gallon portable tanks laying on the rear floor. out in the open. I suppose the original seating was two bench seats, one forward and one at the rear. The tanks were most likely under the rear seat.