23 Bertram/Carribian Stringers and transom

Yes, cover the gunnels. Climbing in and out, dragging abrasive dirty hoses and cables over them, sliding new stringers and plywood for the new deck over them, buckets of resin set up there, resin gets on the bottom of your shoes-you get out and dirt and sand sticks to that-you get back in and leave some stuck to the gunnels...by the time you're done you can easily have another big project just getting the boat looking decent again.

I'm thinking the incy wincy stringers were mainly in place to give a 'level' surface for the deck to sit on. It looks like the old deck intersected the hull a few inches outboard of them. When you install all the new stringers you'll have to do it so you end up with a flat plane side to side and front to back for the deck to sit on.

Defunct batteries make fine weights, good and dense with usually a built in handle.

If (when) you have to fill and fair the bottom, you'll have to remove the trailer and crawl under there so now would be the time to get it all set up safe and ready. Like I said earlier, on 12x30' ocean going boats from bare hull to finished cabin boats, ready to flop in the water and motor away, we just used 3 barrels, like the one on the left side of your photo. It might seem like that's too high, but for all the work I did underneath, cutting holes and installing all the running gear, rudders, shafts, struts, a full length 4x14" skeg with through bolts... all that could mostly be done sitting on a 5 gallon bucket, which is much better than being in the nether zone of on your knees and crunched over or on your back with arms stretched out.

Glass can have a memory, but heat can give it Alzheimers. I had a canoe with a very light layup that I left sitting in the sun on a small rock for a day, and that left a good sized dent. On those 30's mentioned above, the rudder posts went through the bottom about 18" from the transom. Here's a photo of one of the boats....(actually, they weren't deep v all the way like yours, they were almost flat in the back. Very fast for the size and type.)



I used a hole saw for the hole for the post and the thickness of the hull in that area was almost an inch of polyester resin and alternating layers 1 1/2 oz mat and 24 oz woven roving. The rudder post bearing and support was a tube about 6" long with a flange in the center for bolting to the hull. The procedure was to wax up the post bearing and position it so it was flush with the hull bottom, leaving the bolting flange about 2" above the inside of the hull. A 12" square form was then put on the inner deck and filled with a resin- chopped fiber mix like mashed potatoes and packed in there up to the bottom of the flange, to form a reinforcing pad. After that set, the bearing was pulled out and a few layers of mat and wr laminated over the pad, a hole drilled through that and eventually the bearing was bedded on the pad, holes drilled to through bolt the flange and it was ready for the rudder post, etc.

On one of them I mixed the resin/fiber mash potato mix too hot, and when I came back the next day an area of the hull, a little bigger than the pad had sagged more than 1/4", which I then had to grind off and refinish.

So, the whole point of that is to say that heat can make a polyester layup flexible and it will take a permanent set and it can happen overnight. Actually it can happen in the time it takes for a resin mix to build up to maximum exotherm temperature, about an hour more or less. Whether you can use it to solve problems like in your hull...I've never heard of anyone trying it. I don't know how it affects the laminate strength, I can hardly imagine it helps, but a lot of boats are overbuilt anyway. I don't know what temperatures are involved or how they might easily be applied, but a heat gun might work. But my guess is it would make the laminate more brittle, which probably wouldn't be good on your boat.

 

Sam, you and I might have some success "talking" to this hull with heat, to move it back into position, but the average backyard guy is just going to make things worse. I've found heat is a hit or miss thing, unless the distortion is pretty shallow.

I've done it, but I wouldn't want to straighten that hook, on my back working overhead. If the boat's empty, roll it over and work in the down hand position, you'll thank me for it, trust me. Fairing is hard enough, working under a boat and overhead just makes it much harder.

 

Flipping the boat over sounds like something I could do, We're on a farm and have a crane. I'm planing on refinishing the outside of the boat when all this structural stuff is done. The hood/canopy would probably have to come off, and that would make it easier to refinish the interior underneath the hood too.

I guess I will probably get the stringers in first so the boat is nice and strong before I start moving it around again. I'm to afraid of twisting the thing. Could be a while off yet though, only have a week left before I fly to Thailand then work and always seems like other things and people take me away from the boat.

 

I don't mean to contradict any of the good advice you've received up to this point, so I'll limit my post to just the hull malformation. If this were brought to me there's two things I would have to seriously consider 1) How easy would it be for me to correct the hull shape using jacks and straight edges externally along with bracing or weights internally vs 2) reshaping the bottom by hand.

In your case it would seem to me that a few hours spent manipulating the hull to see what affect you can have now while most of the internal bracing is removed would be time well spent. I can even see an opportunity to correct some of the hull form when installing new stringers ie. using them as a means for applying pressure internally over a long span. Once you start glassing in those stringers you're going to lock in whatever hull shape you have...heck you'll probably have to cut the stringers just to get them to fit that hook in the bottom. My advice...take a few hours and see what you can do to straighten out the hull BEFORE you do any glassing. You might be surprised how easy it is to move.

MM

 

what he says....midnitmike....the bottom will be very flexible now that the thing is empty, you can easily reshape the bottom, normally you would have to be very careful doing this sort of work to NOT shape the bottom adversly.

drums of water (20 litres) places strategically inside will put 20 kg on each patch.

 

Having "reshaped" a number of boats, I can tell you straight up that jacking and placing weights will do little. It'll just pop right back to it's "set", unless held there through dozens of heat/cool cycles, such as that seen in a few years, on a poorly fitted trailer. You can accelerate this process with heat, but taking a guess at the plasticity temperature that will effectively work, is a crap shoot and you'll likely just cause more distortions, unless you have a mold to smash it into.

With the hull upside down, the fairing process is pretty straight forward in this portion of the hull. The run will be dead straight fore and aft and the deadrise will likely be so too, or nearly so. This is as easy as it gets, from a fairing point of view (down hand, straight line work).

The usual keys are the keel and chine lines, which most of the time are okay. These areas have enough meat in the laminate to resist major movement. It's the unsupported spaces between the stringers or where stringers are rotten, that usually see the most panel deflection. Rollers are notorious for this and have bent many a hull.

A straight edge on the keel is my first tool and it gives me an idea of how much things have moved. The chines are next, though these often have some sweep to them in the midship sections, a sweet curve is easy enough to identify. Strakes and the flat areas between them are the usual places things move.

If the keel and/or chines have moved, on severe cases some relief cuts can be made, the hull jacked/braced back into position and new "bridging" laminate applied to lock it down in the proper location. Then it's just a mater of fairing it up.

I really can't tell from your photos, but the keel looks like it's still straight, maybe with a slight hook just forward of the transom, that can be filled in, but the keel at the transom and a meter forward of this looks like it can be filled and the hook removed. The strakes will need to be straightened in the process, as will the areas between, but all normal stuff.

 

Par,
While I have the greatest respect for your experience and wisdom in these matters I must disagree that the OP's only option is to refair the hull after installing his new stringers. While I can't state catagorically that he will be able to return the hull to it's previous shape I do think he should at least explore his options before he commits himself further. It may take no more observation and testing then have someone stand inside the boat to see how much affect their weight has on the bottom.

He has already mentioned that he intends to remove and replace stringers indivudually so as to minimize any twisting or deflection in the hull. And "IF" his hull were in perfect condition I would agree with his cautious and conservative plan. But as we can plainly see from the photos the hull has taken an unfortunate set due to poor trailering in exactly the areas you describe as being the most commonly affected.

If the OP were to remove the rest of the stringers and attempt to realign the hull prior to installing his new stringers he may find that he can live with the results. Personally I wouldn't use weights (water or batteries) to try and reshape the hull... they just get in the way when I'm glassing in the stringers anyway. A nice chunk of 6" I beam and a couple of 12 ton bottle jacks is more my style. If he can't straighten out the bottom of that boat using that...then by all means flip it over and have a ball. After all not many guys have a crane at their disposal, so why leave a good tool unused.

Even if the OP can't return the hull to it's original shape using my method he will at least remove some of that nasty set...making his fairing job just that much easier. All I'm suggesting is that he take his time and explore a few options before moving on and commiting himself to a course of action that he may later regret.

MM

 

Mike, you can jack and weight all you want against 'glass, but the moment you remove the pressure, it'll return to where it was, assuming you haven't broken laminate bonds, in the process of trying to force things back. Heat does work, but it's very difficult to control the process and you usually end up with more distortions in other areas, as well as some movement in the areas you attempted to affect.

Forcing the hull into shape and bonding in stringers will help to some degree, but this preloads the structural elements, which isn't good. The best choice is to bond in the stringers, as the hull is, distortions and all. This will lock the hull down and then fair the exterior as needed. This is simplest and fastest way.

Some, including myself and only on severe cases will cut the hull. These relief cuts will let the hull "relax", so it can be easily jacked or wedged back into position. This is a drastic measure and you really need to know where to cut, or you'll have a much bigger problem.

The photos, don't look too bad, so slap some stringers in her, slather on some putty, fair her out and she's ready for paint.

 

"photos, don't look too bad, so slap some stringers in her"...my thoughts entirely, that is why I suggested some weights when the stringers go back in to force the shale into convex whilst the glass goes off, it will stay there after that.

 

Well sir you make a very persuasive argument.

I will only point out that it was never my intention to try and force the glass into a state of submission such that it would retain it's shape without additional support. Only to preload the hull so that the stringers could be installed on a relatively flat surface. Granted this might not be the ideal situation, but given the fact that this is a 30+ years old boat, and the malformation seems relatively minor I doubt that he would see a catastrophic failure of the stringers once the pressure was released. They were after all 6" and 8" deep...more then sufficient to contend with the forces involved here.

Although it's difficult to determine from the photographs an exact measurement of the curvature it looks to me like it's about a 1/2" more or less. With that in mind even a small gain in hull fairness might be enough to satisfy the OP that his task has been accomplished and allow him to move on to his other projects. As you said it doesn't look that bad and I agree completely, so why not see if he can pull it into line before glassing in the stringers.

Granted this isn't my boat, and it isn't sitting in my yard waiting for me to walk out the door. But if it were I know exactly where the jacks and steel beams are laying (albeit under the snow at the moment), and what I'd be doing for the next couple of hours.

MM

 

Agreed Mike, trying to get some of the distortions out of the hull could prove to ease fairing operations, I was just warning about what often times happens in the back yard. What I mean is, "if a little pressure did this, I wonder how triple the pressure will do . . ." It's easy to get greedy with this sort of thing. I am reasonably confidant he's not going to "pull it into line before glassing in the stringers" as 'glass doesn't respond like that, once it's taken a "set", but he could use a little per-load to save some fairing effort.

 

Hi everyone, I really appreciate all the constructive discussion on this thread about my boat.

I think I'm going to just flip her over later with the crane. It makes sense to me that if I manipulate the hull into position then set in the stringers, there will be tension in there and I rather not have that. And knowing what I'm like I probably won't be satisfied unless I get it straight.

I'm lucky I have access to farm machinery so I should take advantage of it and by flipping the boat over will also make it easy to repaint the underside. When I get closer to that point I hope people don't mind me asking for some ideas on how to do it without damaging it. For now I'll just get these stringers in.

Today I made some good progress.
Added some more thickened epoxy to get the fillet smooth on that transom because I wasn't satisfied, finished of the inner stringers inc bulkheads and tested fitted them. Tomorrow I will sand the transom flush then fiberglass the transom in and probably a bit of work on the stern drive if I have the time.
One thing that annoys me with this epoxy is the fact that I always have to scrub off the amine blush before I start sanding.

I forgot to take pics today, will get some tomorrow hopefully.

 

If "peel ply" is used , blush becomes less of a issue. Pickup a few meters and give it a try. Its Easy to use.

Google peel ply for more info.

For areas not suitable for peel ply.. working wet on wet is best