creosote problem

[dimdim]

Hello all, I'm a relative newbie to this boat life

my question is as follows (forgive the ignorance)

I have an old timber boat (1956 Tasmanian built) which has the hull soaked in Creosote - the boat will be used in reef areas in PNG - inevitable to "kiss" a few.

the hull needs to be strengthened - I plan to thicken it from the inside

what could I use to glue the strengthening timbers to the creosote soaked hull?

I plan to lay them on top, parallel - and then add extra ribs on top.

the boat is driven by a 6354 perkins

thanks to all

[rasorinc]

In my first search for an adhesive to stick to creosote coated wood I did not come up
with any good results. You may find an adhesive but you might have to back it up with mechanical fasteners ( nuts and bolts )

[Frosty]

Why not just plank over the outside with bolts and a traditional oil based caulking compound. Maybe sister a few ribs in as well if you want.

[PAR]

I wouldn't go crazy here, as it's a common misconception of boating novices, to think they need to "beef" things up. Most hulls can be protected with chafe strips on the keel, along the turn of the bilge, etc. without resorting to doubling the wight of the planking with another layer. Call a qualified boat carpenter and have him look her over. If he's got any real experience, he can tell you the right way without the expense, effort and burden of an additional, sacrificial layer of planking.

[dimdim]

Thank you for the replies so far.

to clarify my reasons: the boat will be used by local fellas when finished - as an island trade boat / transport for our college needs. As much as it is slightly pessimistic - this boat will end up on reef, either at 8knots or at anchor. I am on a limited time and financial budget - thus I was thinking of layering off-cut timbers between the ribs (the boat is completely gutted included deck) and then adding a few extra ribs on the topside of the hull to brace them at each end of the new planks (hardwood 70x35mm on the flat)

I can epoxy the planks to themselves, but need a way to chemically bond the creosote hull to the new planks.

I researched some American forestry sites, and they said in one of their papers that HMR HydroxyMethylated Resorcinol could be used to "lock up" the creosote planks before using glues - haven't been able to source anything here in Brisbane, and it seems it is all too hard for the epoxy resellers.

i thought about "tar" as a medium, but was told the new "tars" are not the same stuff, and would be melted by the creosote. I shudder at the cost in time and resources to re-plank the whole hull with stronger timbers.

there must be a way - I just need to find it.

thanks again everybody

[troy2000]

I'm not a professional boat builder, but I've been playing with wood on dry land since about the time I started talking. And I personally have never found anything that would reliably stick to creosote.

Then again, it's possible I just haven't kept up with the times, since I don't do construction professionally anymore....

[PAR]

Again, instead of making additional "hard points" inside the hull, which will just test the existing planking fasteners pull out strength and saturate existing frames with more fasteners, just apply external rub strips in the obvious locations. These can be fastened to both the planking and existing frames, it doesn't add much weight, nor increase point loading on the planking. They can be removed and replaced as they get torn up, they keep the planking from getting dinged up. The rub strips can be any length and butted together. They can also be junk wood and more frequently replaced, though typically you want dense hardwoods. You could even use HDPE or other dense plastic as the rub strips. Trust me, this is the economical method and you don't have to crawl around in the bilge, trying to sister frames in awkward locations.

[Frosty]

Most boats suffer if run up on reefs but they dont strengthen the boat but get a new driver. Your curing the symptoms and not the problems.

[thudpucker]

Are you sure it's Creasote and not Pine Tar?
PL (polyurethane) will stick to wet surfaces. That might help with casual leaks.
I thing PAR is steering you right about the Beefing etc.
Get it into the water and do some exercizes with it to see if you actually have to do anything at all.
Remember, we like Pichers

[waikikin]

Originally Posted by PAR

Again, instead of making additional "hard points" inside the hull, which will just test the existing planking fasteners pull out strength and saturate existing frames with more fasteners, just apply external rub strips in the obvious locations. These can be fastened to both the planking and existing frames, it doesn't add much weight, nor increase point loading on the planking. They can be removed and replaced as they get torn up, they keep the planking from getting dinged up. The rub strips can be any length and butted together. They can also be junk wood and more frequently replaced, though typically you want dense hardwoods. You could even use HDPE or other dense plastic as the rub strips. Trust me, this is the economical method and you don't have to crawl around in the bilge, trying to sister frames in awkward locations.

DimDim, take note of this advice, Australian hardwood decking material would be cheap & easily available. Regards from Jeff

[dimdim]

thanks to all,

changing the crew is not an option - all crews are the same - even the swish knowitall experts come here and kiss reef from time to time. this boat will be a genuine non stop / all weather workboat.


I will put the rub strips about 10 inches apart? it would need to be at least 50mm square, and screwed through the planks into the ribs, using some sort of tar as a medium?



thanks again for the practical advice, it's much appreciated

dimdim

[PAR]

Faster to the planks only and use fasteners that don't go all the way through the planks. This way if you bash something hard and tear one off, it will not leave a hole into the the boat, just some gouged planking where the fasteners ripped out. These are sacrificial in nature, so keep this in mind.

10" on center seems way over the top. Each hull type will have obvious places under it where it will likely bash into things first. This is where the strips go. The whole bottom doesn't need these strips, just the likely locations where it'll challenge sea life and terrain.

[kach22i]

Originally Posted by PAR

just apply external rub strips in the obvious locations.

This is the 2nd or 3rd time I've read this type of suggestion, and I have to agree with it.