Rotten frames at keelson, in concrete!

Seagreen

Seagreen

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So, here's the problem.
Bought a venerable old boat, (about 140 years old- madness!) last May and though I had her surveyed, the surveyor could not check all the frames. The previous owner had completely retored the boat in the last 15-20 years, vouched the at all the suspect frames had been replaced or doubled, and then had "replaced the concrete and scrap ballast as found" back over the keelson.

So now the boat's ashore till april, with large refit TLC planned, I find the time to rip up all the boards and have a good poke around and find the nasty surprises...

...Which aren't huge but will be a problem. Two frames either side of the boat forward of the mast are gone competely where they enter the concrete, but are sound above. Two more frames on the Port side are a bit soft in the external timber. The heel of the mast is set up in another larger concrete block, though there is a galvanised frame between the two new ring frames that support the mast. I know the previous owner didn't salt through the hull (naughty) but I suspect that its really a reaction between
the timber and the concrete.
My normal response to this would be to remove the garboard and next planks up, and hammer out the concrete and re-frame. But if I was going to all that palaver, I'd reframe the lot and time and funds do not run to that at the moment.

There does not seem to be much movement in the heel of the mast, even when wanging through a 60degree arc in a heavy beam sea, the boat didn't take much water on, so I'm confident that the heel of the mast isn't moving much.

Back to the rot. The BIG IDEA, given that I don't want to rip out the garboards, etc., is that as a temporary measure, I will cut back to sound wood, and then removing all the rotten frame - the fastenings were all removed and replaced by copper 15 years ago- so leaving the frame "hole".

Plan is to scarfe in a piece into the good frame and filling the hole with part of the scarfe but the void filled with an epoxy plug. I'm planning to dry the hull out for a few months so that this won't cause adhesion problems, and drenching the area with a rot preventative weeks beforehand.

All advice gratefully received.

Mac /forums/images/graemlins/smile.gif
 
Depends on the type of concrete used for ballast - from the sound of it, yours is the wrong sort! The right type of concrete is fine......... that used on Excelsior has been OK - the point is that if your predecessor used the wrong stuff you are wasting your time and money on repairs unless you remove the concrete. Will try to obtain details.

Old Frank
 
Umm. A bit familiar.

Had two rotten frame ends at the cement and a rotten mast step.

Remedy was chip out the cement and renew, then replace cement. I very strongly suspect that this trouble comes from a fresh water drip above the affected part; if water can lie adjacent to the timber this may do the damage.

In my case the rest of the oak and CRE framing and teak planking and keel was fine I have no doubts about the merits of cement flushing through the bilges in principle.

Teaching grandmother - use a long, thin, cold chisel and a club hammer!
 
Ok, here is big dummy question of the week! Why would anybody want to fill the bilges of a wooden boat with concrete? /forums/images/graemlins/confused.gif

Surely if the timbers can't breath, they will rot?
 
Ballast. If your boat doesn't have a ballast keel then it will have to be internal. Either pigs of iron/lead, stones or concrete. In the very old days stones were used. The best is pigs of iron or lead held in place with concrete so it doesn't all fall through the deck in the even of a knock down.

Usually it helps preserve the timbers, because while air can't get to them neither can fresh water. In this case it would seem that fresh water has been sitting in the bilge and has rotted the timber at that level.
 
I didn't think there would be any boats still afloat that didn't have an iron ballast keel!........Ah well, ya live and learn /forums/images/graemlins/smile.gif

Are we talking early yachts here or ex working craft? From when would it have been common practice to fit an iron ballast keel?
 
External ballast keels start from about 1880, for racing yachts. Nevr used uin fishing boats - sailing trawlers were being built with all inside ballast into the 1920's - and only one Bristol Channel Pilot Cutter (not one of the survivors) had an external ballast keel.

Immediately before the 1880's, the practice for racing yachts was to coat the frames and planking with clay and run the molten lead into the boat. This was a bad system as the clay washed out and the gap left behind between lead and wood was a foetid breeding ground for rot. See Claud Worth for a good description of te consequences, as experienced by him between Ireland and the Scillies!

Another reason for cement in the bilge, also covered by Worth, is to allow the bilge water to run clean to the pump well and not to sit around and get stagnant. This is particularly important in boats with steel strap floors as unlike wood floors they cannot have limber holes. My boat has this system, and has cement inside.
 
Thanks Andrew,

This site can be really good at times, especially this forum, all ya have to do is ask! /forums/images/graemlins/smile.gif
 
Not strictly true on the fishing boat point. Colin Archer was building fishing boats with ballast keels as early as 1895. The main reason they were mostly found on yachts instead of workboats was solely down to cost. Simply put when having their boat built most fishermen, pilots etc couldn't afford five or six tonnes of iron to strap to the bottom, so instead scrap iron and concrete was used.

Some of the ballast that comes out of a Bristol channel pilot cutters ballast has to be seen to be believed with bits of machinery and everything in there. On one occasion when breaking one up they came across an artillery shell.

While we're on Bristol Channel Pilot Cutters, of the survivors only Dolphin has a ballast keel. But it is not known whether this is original and it is likely that is was added after she was converted to a yacht. The presence of the ballast keel is the main argument by some who don't believe she really was a Pilot cutter.
 
Concrete was very common East Coast work boats. The main reason for using concrete was to make it easier to shovel out the catch/oysters from the botttom of the boat more easily. It was also normal to leave concrete out between a pair of frames aft to provide a well for any water to drain to. The pump well. My previous boat built on the southcoast in 1911 was built with a lead keel, and was bronze fastened throught. No concree what so ever.
When I removed the concrete from Transcur's bilges having previousley removed the garboard and next plank up, I used a heavy lump hammer, occasionally a sledge hammer to break up the concrete. The frames exposed were very sound. None were rotten, in fact the oak was still quite white for a few minutes then they went black on exposure to the air. Most of the wood above the concrete was completly rotten. I have put concrete back now.
 
My yacht was built in the 1880s, and has an external iron keel and lots of internal ballast. When I bought her this was a mixture of odd-shaped pig iron, broken bits of foundry grate, gearwheels, general machinery junk. I've now rationalised this and mostly replaced with old sash weights of suitable and varying length. It is all packed tight in the bilges, held in place by frames and cabin sole.
I've wondered about concreting it in, but one major disadvantage would be that any bilge water would then lie on the cabin sole, instead of underneath it.
There would also be the compliaction of providing access to seacocks, which of course would then form permanent sumps for bilge water.
 
Thanks for all the comments, but I'd like to bring the topic back to the start point. I'm not intending to take off the bottom planks and hack out the concrete yet. As its a concrete and scrap mix I'm leaving that palaver till its really necessaey, and then I'm just going to do the whole lot... As the hairy one in Scooby Doo says - "Yikes!"

I'm looking for opinions on my "interim solution". Which is:

Reaming out the rotten frames at the keelson, and scarfing in frames using epoxy to fill the voids around the scarfed ends and fastenings at the keel as "instant frames".

The object being to secure the good section of the frames into the keelson end ending any possibility of movement in the area.

Is this a good or bad idea and what possible problems could I encounter?

Mac /forums/images/graemlins/smile.gif
 
Cheers lakesailor, I'll chase that up! /forums/images/graemlins/wink.gif

In addition to what's written above, I'm quite happy with the vast majority of the concreting. The whole restoration done between 15 and 20 years ago was very well done. The mast is supported by 2 ring frames and a galvanised steel saddle over a further concrete block to prevent the heel of the mast moving, and there are limber holes both sides to allow any billge water to drain away. Altogether a good job, but its these two plus a couple of other possibly dodgy ones which need bolstering. All the iron fastening were replaced with copper, so would encasing these fastenings in epoxy cause a chemical reaction?

Mac /forums/images/graemlins/confused.gif /forums/images/graemlins/smile.gif
 
On the subject of Bristol Channel Pilot Cutters....
Halford's yard (based in Gloucester at the head of the Bristol Channel) built pilot boats with both internal and external iron ballast. 'Carlotta' is a surviving example.
Also the BCPC "Faith" was built with external ballast.
Bristol Channel Pilot Cutter CARLOTTA
 
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