Need ideas with timber hull

Hi i am hoping someone out there might get me started on the timber before i fibreglass.I have a 33ft sharpie design old work boat .I have finished the top and need to start on the hull .It is about 6in x 1in vertical planks running up from the timber keel they have dried out leaving a range of gaps up to half an inch . I have been given so many different options ,from sikaflexing the gaps and then ply then fibreglass ,to putting in oregon wedges glued in to gaps sanded undercoated then fibreglassing . people have given me downsides to both of these options so i hope someone may be able to help Thanks Ross

 

This is a common subject here. You can use the search tool and get some back ground, from previous threads on the subject.

As a rule, the construction method your boat uses doesn't blend well with plastics such as miracle goop in the seams and/or 'glass sheathings.

There are several reasons for this. Folks that do perform this to their traditionally built vessels, have only two possible routes to success. The first and likely the most common, is to get a few more seasons worth of use from the old gal, before they drag it to the land fill. The second and commonly seen on workboats, in an attempt to give them a cheaper second lease on life, is a thick 'glass sheathing.

A light sheathing (anything less then say 18 ounces of fabric on the exterior of the hull) will keep the water out for a while, but the issues that haunt the structure still remain and deterioration will continue, though contained within a thin plastic skin. Eventually catastrophic structural failures will collapse the frame work and the boat dies, though fortunately there's a handy plastic sheathing that will contain most of it, while it's dragged off to it's final resting place.

A heavy sheathing can add some structural integrity to the hull, but since the hull isn't designed for these types of load transmissions, it starts having new problems. You also gain a considerable amount of weight with this technique. A plywood skin, attached to the old hull and then sheathed (to protect the plywood) is an option, but again a lot of weight to burden the hull with.

In the end, 95% of the time it's less costly to just properly repair the boat, then it is to invent new ways to expedite it's demise in hopes it will save it.

To sum up, you can get a few extra seasons of pleasure from the boat with a light 'glass sheathing, but the boat will suffer badly as a result. If this is all you want, then it's an avenue to travel down. If on the other hand, you'd like the boat to last, say 10 years, you'll have to use a heavy sheathing, probably coupled with a plywood sheathing to stabilize the planking. Assuming the original wooden structure doesn't fall apart within the new 'glass sheathed plywood hull, you'll have some years to enjoy.

Bluntly, repairing the real woos of the boat will be less costly and better for the structure, then burdening it with more weight and plastics, that will not let the wood do what it must, which is move with moisture content changes.

 

I agree with PAR. The best way would be to properly repair the wood structure. Don't look for short cuts or band aids. I the long run the work of repairing it correctly will be well worth it and provide a long life for the boat.

 

Thanks for the reply are you saying that i should re cork between the planks then or do you have a better way Ross

 

Thanks for reply

I just wanted to add that the timber in the hull is in good condition and the planks are as well ,it was calked if that is the right word but i thought that you would not re do it because of new ways

 

Hi i would be very interested in gaining some knowledge from you but i am struggling to find my way around this site Ross

 

Caulking and fastener tightness are the keys to a solid structure. One can't be effective at keeping water off your socks without the other doing it's share of the work.

The first thing to check are the condition and tightness of the fasteners. If tight, it's okay to caulk the boat, but by your description of the seam gaps, it sounds like you have other issues. Which issues it might have are difficult to guess, without pictures or a better description of the structure's condition. Gaps that large often indicated broken frames, sagging bilges, hogging, etc. You should have an experienced boat carpenter come out and look her over. This should be a person experienced in traditional construction.