How to proceed after hull extension mold error

Just cut the corner like wf suggested to each next element or about 30" or so; push the corner down 5/8" or so; then reglue the corner with thickened epoxy in a couple spots, let it cure and then make a nice fillet and addback about 2-3 layers of staggered 1708 tapes to the inside over the fillet. Flip the boat over, then grind it clean and fill and tape 1-2 tapes outside. Each tape is 25 oz glass so get close to build spec in new laminate thickness. Then fair it to perfection. A square transom edge is ideal for planing hulls as well.

 

Cutting and reshaping is a hassle, but relatively easy, cut where needed, line it up, glass it back together, done.

 

Thanks all. So it is a little high under the stringer, maybe 3/8”-1/2”. What should be my approach? Do I cut the bottom inside right up to the stringer or a couple inches away from it? Do I consider cutting the hull off the stringer completely? (That would be a small slice of total misery) If I cut the bottom at the stringer I’ll have a small wedge area I’d need to fill in on the bottom but I do t think that would be any big deal.

cut like this? I can cut the bulkhead tabbing so I can flex the whole area.

 

How thick is the laminate?

I'd probably flex the BH, but probably not go past the edge of the stringer with any cutting.

You have to do some fairing now; so there is no reason to try to separate the laminate from the stringer or cut things too close to final.

 

1/2” give or take, could be more but certainly not less.

 

1/2" thick laminate is like 10 layers of 1708, so that is an awful lof of cutting at the stringer...I might measure to be sure you are 1/2" off before cutting at the stringer

 

Ok, I think I just need to get cutting and see what I can do….

 

Do not cut the horizontal surface.Cut the fibres that prevent the bottom panel from being moved-that is to say at the bottom edge of the stringers and bulkheads inside the hull.The whole point of the remedial work is to move the bottom surface of the boat to the position it should have been in and cutting through it will create a lot of unnecessary work.By severing the fibres that hold it in place,a green laminate shouldn't be too hard to move with a handful of strategically place wedges in the cuts you made.If the bulkheads are bonded in with 1/2 inch thick glass,you overbuilt massively.Which may make it hard to move a very thick bottom panel and lead to the situation where you need to cut part way through the hull laminate at the point where the panel has to pivot from.Not that difficult but messy and tedious.If its all epoxy,be sure to cover yourself as green epoxy is quite dangerous from a sensitising perspective.I really don't know why so many amateurs are in love with it,unless its a desire to have the "best" when bragging about their boat.It has it's uses and ought to be confined to those things it is needed for.

 

So, if I am reading wf correctly, he is suggesting to NOT cut vertically into the horizontal surface, but to only cut horizontally and separate the laminate from the structures while keeping the laminate full thickness.

I agree. Those cuts will be harder to do well, but then the laminate will remain intact. And at the bh; you lower the entire bh and not cut at all. I would use an oscillating tool with a carbide 2" wide head. It will be tempting to try to cut all the way, but the cutting head will impart too much heat, so you'll want to cut in a way to avoid melting goo onto the tooling

In this case, then you can cut and separate the laminate and keep a full thickness off the bottom edge of the stringer.

@wet feet ~ a lot of amateurs use epoxy for easy mixing and lower odors in a home garage~bond strength is higher if it matters, of course, as well

 

Ok, I want to ask about option #2.

What is the downside to adding material to the bottom to re-contour it?

 

Weight and cost is all. A piece of 1708 is about 50 ounces per sqyd at 0.050", so to make 0.650 is about 21 layers or 1000 ounces or say 60 pounds.

If you can to put a piece of foam core in there; you could. I would probably use 1/2" and then 3 layers of glass. Bond the foam in by prewetting both surfaces 30 minutes ahead of the work or an hour for slow epoxy, then use a 1/8" vee trowel or two 1/16" and both sides and a lot of fumed silica. I prefer the 1/16" to each side.

After bonded, grind the foam to zero on the sides and Stagger Bond the glass.

sorry for grammar, am super busy

 

Enough weight to unbalance the boat? Any reason not to use something light as core and a couple layers for the outside skin? It’s like 9 square feet. Should just be a few layers for an outside skin?

 

What I am describing is separating the bottom panel from the bulkheads and stringers-so that the entire distorted section can be pushed into place.fill the gap that this creates and re-bond with a sensible amount of glass.Even icebreakers don't proceed into ice stern first.

Adding lots of layers to the underside of a hull is a miserable and messy process.so is achieving a good finish.Try it and I doubt you will ever want to repeat the experience.Inverting the boat to make it easier is no minor undertaking,even with overhead cranes.Without proper lifting equipment you may have all kinds of mishaps.Your boat-your choice.

 

@wet feet Let’s try and sum this up with pictures. Hopefully a picture is worth 1000 words. If I understand correctly what I’ve been trying to understand makes sense.

I’d separate the bottom panel from the stringer and bulkhead at the blue line. I believe I’d need to cut through the bottom panel at the red line at the transom and possibly the chine. Then it’s just a matter of fillet-ing and tabbing them back inside and out and fairing until my hearts content….
Does that sound like I understand?

I do have access to the proper lifting equipment and that was the next step as the bottom needs enough work that I don’t want to try it upside down so I can go either way. There is something appealing to a newby to not cutting into panels but that’s mostly lack of experience.

 

Close,I'd cut the transom rather than the bottom,but it looks unbelievably thick along the upper edge.If its that thick all the way down,it would be easier to cut the bottom but the finishing work goes off the scale.The entire aim is to free the portion of the bottom panel that needs re-aligning and to bond it in the correct location.Creating the minimum amount of finishing will greatly reduce the amount of time that the boat will be out of commission.Having the lifting gear is one thing,but have you ever inverted a boat of this size?Transverse movement of the lifting gear is pretty much essential.