Another 1980 Stringer

I am finally getting to the point where I need to start taking the stringers out, or patching them up. So far I don't see too much rot, just the top of the starboard side where one of the floorboards was rotted and the rot went into both the primary and secondary stringers.

I will drill some holes in the next day or two to see if there is rot or not. I have read most the stringer posts and it doesn't seem that anyone has just patched up what's there - so I assume the consensus is since the floor is out one might as well do the whole thing anyway?

Picked up a hole saw for the drill today but too late tonight and on the road for the next couple days.

The front of the primary stringers quite visible (not a lot of fibreglass) - hard to see but the starboard side has some rot near the front end where the last floor board sat.


here the secondary stringer looks like it just came from the mill....



but farther forward it is 'weathered' but still appears competant,


I'll see what the holes reveal later this week.

Also - the diamond blade on the grinder seems to be the way to go to remove the stringers based on other posts - any suggestions appreciated as this part is getting scary to me.

Those suggested glass schedules are VERY light... I would do some reading up on the stringer rebuilds shared on this site and come up with a proper glass schedule, and then base your material list off of that. US Composites has great materials at great prices, but their tech support is very hit or miss, it seems. This is one case where I would give them a big .

Before you get to the point where youre creating a materials list, you need to decide the method youre going to use to rebuild the boat. Maybe youve done this already, but feel free to clue us in.

1. Wood vs. composite
2. Foam vs. no foam
3. Floor material (glass over foam vs. plywood, etc)
4. Extra structural members (ribs, bulkheads, etc) or not? (Largely dependent on your answers to 1-3).

Those will drive your material list to a great degree. For a "factory" stringer/floor job (wood stringers, foam, glass over foam floor) then I would say that 10-12 gallons of epoxy (not including the hardener) is in the ballpark. Other methods may require more.

I agree that shooting for a glass thickness similar to the factory is a good idea. If using all cloth, that will likely take 10+ layers (probably closer to 15). Certainly nowhere near the 2 that USC recommends. If mixing in some mat or biax, then 5-7 layers may be more appropriate. The fact that they think 2 layers of cloth is sufficient is just downright scary... maybe for a lightweight outboard that doesnt have a V8 resting on the stringers, but not for a stiff-hulled inboard, thats for sure.

Have you read any of the stringer threads that discuss glass layup schedules? I dislike your proposed schedule for several reasons- thick layers (biax, mat) are harder to work with as they don't bend well. Following a thick layer, it is very easy to introduce air bubbles where you stagger the joints. Cloth is probably the worst choice for a finish layer. The common biax used from USC has cloth woven at 45 reg angles, so you wouldn't have many layers with their greatest strength in the most important directions. Your proposed layup will be about 1/8" or so; not approaching 1/4".

That's thefirst Ive heard of epoxy having a 1 yr shelf life... I too, am skeptical! Ive used older stuff without issue.

No way would I grind inside the garage, what a mess!!! You can remove the stringers and then brace the hull afterwards. That would allow you to keep the boat mobile.

Gary S wrote: TRBenj wrote: That's thefirst Ive heard of epoxy having a 1 yr shelf life... I too, am skeptical! Ive used older stuff without issue. Gel coat is the same too,it says 90 days but I have had 1 can going on 3 years. I have always used this stuff,it seems to work

I've got epoxy that's still good and is at least 5 years old!

Gary, I've used the technique of removing the oxygen from cans for years however, I don't buy the expensive little cans. I always have a bottle of MIG shielding gas (75/25 for carbon steel and the "Tri-mix" for stainless) and use it to evacuate the oxygen. Getting the oxygen out of the partially filled coating cans does work.

I like the doubled up 2/4/8 cloth on the stringers much better than multiple layers of thicker material. I would add biax up the side of the stringer, as well as capping the tops of the primaries with it.

On the floor, youre correct that the 3 layers of biax would be 1/8". Mat is thinner than biax and a single layer of cloth will add next to no appreciable thickness, so you'll be just a shade beyond 1/8" with that layup.

I think that biax on the floor is overkill. The reason for a thick build up here is more for impact resistance than pure strength. I would opt for alternating layers of cloth and mat instead- you'll get plenty of strength from that combo, and mat builds thickness pretty quick. Its really no harder to work with than biax- it actually forms bends a *little* easier, as its not quite as thick. Mat is also significantly cheaper than the biax. 3-5 layers of alternating mat/cloth on the floor should be fine- starting and ending with mat.

Chuck,
I think this is the first time I've heard anyone doing a stringer job having a problem getting the old ones out. It's got to be a combination of them being in pretty good shape and the factory doing a unheard of good job! I'd draw a straight line lengthwise down the stringer for future reference. Then, cut them into about 3 sections. With the line drawn on the old, you can then clamp them off to a straight edge and use them for templates.

If you're sure you're through the glass on the sides, then I'd be inclined to break out the sledge.

Okay Got it out intact. Two additional hours cutting with the diamond blade and grinding (sanding) with flapper wheel thing and a couple gentle wacks with a (small) sledge and out it came. Perfect condition for a pattern. Was not stuck at all along the bottem just the glass on the sides holding. No wonder this boat weighed so much it seems to be bedded in an inch of glass.

The secondary stringer is in tight too. An hour of grinding and just starting to get some movement - probably another hour there. Hope to get it out and all the misc plywood by the time we take off for a couple weeks at the lake at the end of the month.

The stamp on the wood indicated select structural grade Douglas Fir, S Dry (<19%) as supplied 30 some years ago. The WCLB is the West Coast Lumber Bureau (as the grading agency it seems) so I guess they (CC) were shipping it across the country.



And now I understand the icing sugar donut comments from previous threads. Good thing I didn't try this in the garage.


Got the order in for US Composites -$350 shipping here is still better than local pricing. Still need to find a good source for CPES (local about $80/qt). I'll be back with some questions when I think I have got the hull ready to epoxy to.

Have gotten only maybe 5 hours work in the last month - although hopefully getting close with the sanding/grinding for the port side.

I cut out the rear lift wood the other day and the plywood was not really rotten at all - the heads of the bolts were pretty deteriated though.

I somehow thought the bolts would be only through the second smaller piece of plywood but they were simpy counter sunk through both.

The interesting thing is that he back piece of plywood seems to have had saw cuts every inch or so maybe 1/4 deep (except for the top ~5"). Anyone know why? I was thinking that maybe the thought was to have the fibreglass go in those groves to provide some mechanical grip (if so didn't work).



Also, finding that behind almost every piece of wood removed there is a layer of what I am calling 'rotten fibreglass' - looks like cloth with the resin extracted. Behind the plywood for the lift ring angle holder it was pretty consistantly 1/4" thick! Also under the stingers for a large potion of the length and some under the rudder wood. Is this from water damage or just not wetted in the first place?



Anyway - thinking I am getting pretty close to where the port side stringers can go in.



I think I have collected about 5 gallons of fibreglass dust so far - not to mention what has blown away or I've washed out. Hope to get another half dozen hours into this in the next couple weeks or it will be mid August befor I can do it....

That's a lot of glass that wasn't wettted - not a good process I guess. Any ideas on the slots that appear in the back of the board and whether I should duplicate?

I'm surprised that rudder port was dry.

I agree with Tim(I know yall already worked this out), the thinner materials are much easier to work with. A lightly routed edge on corners also helps.

Chuck,
I don't really know what you would gain by adding the extra hull drain. The low spot is where CC installed the garboard drain towards the front of the engine.

With the epoxy with the cold weather, just go with a quicker hardener.

Hey, so far it's looking great!