Thread: clinker leak

SILICONE WOULD BE Bad bad bad bad bad form i'm afraid! BUT YOU MIGHT GET AWAY WITH SIKAFLEX! ;-) (Edited because I'm a goose who didn't read the question!)

Read this for an explanation.

For a solution? Well we'd have to know more about the problem.

cheer,

P

Hi Graham,

Any ideas where it is leaking? Does he normally keep it in the water or on the trailer? What timber is it made from?

If it is kept on the trailer and is being "dry sailed", throw a couple of buckets of water in the bottom of the boat the day before it is being used and she should take up and stop most of the leaking when it is used. If it is leaking whilst it has been in the water for a while, there is a problem somewhere that needs to be addressed.

If it a rough old clinker boat that your friend wants to get a little bit more life out of - sure sika it. If you/he hasn't the time/money/inclination to chase the leaks and repair the boat sika will be fine. If you are going to use a bit of sika, tape off the seams on the outside of the boat to leave a thin line along the lap, prime with sika primer for wood then apply a very small bead of sika. It will not need very much and I would only worry about the seams below the waterline. Clean up with some turps and allow to cure before painting. Better to use sika than epoxy.

If it is a really nice boat, I'd be finding the leak

Do you have any pictures to show??

regards,

AD

Howdy - Sikaflex and Silicon are different animals.

Silicon Sealant is the spawn of the Devil. But Sika can be very useful in the right places

I would first opt for a conventional repair - particularly if it is only a localised area.

Is the boat kept on a trailer or in the water?

If it leaks from lots of places then you can do quite a good repair by raking out a slight groove on the plank that overlaps on the outside to make a groove maybe 4 or 5mm deep by the same wide - this give a bit more surface area.

Then you need to use the right sika primer - to make sure that the following sealant sticks to the surface. Then follow with the right sika sealant.

There are different sorts of sikaflex for different applications - you need the right one - some don't work so well under water.

This can work OK when a boat is trailer borne and drys out between uses - I am always a little reluctant as it is nice to keep a boat as original as possible - but where there are lots of leaks - it's not bad.

MIK

Iam confused P, you say " bad bad bad" but your reference seems to confirm that the sika is ok, ? what am I missing here. Mik, Iam working on the photo. graham

Mik, The boat is kept on a trailer and I understand that is a problem however it is a nice little boat but nothing extra special. The leaks are not bad but I thought it would be a bit of extra protection seeing as i was painting it. The leaks are on the seam of the second & third plank down., one on either side of the boat. Graham the photo should be here

Silicone sealant is made from .... silicone and it has the problems of unpaintability, not very strong adhesion, cant be tidied up by sanding.

Sikaflex is a brandname for a polyurethane sealant which grips quite well - very well if you use the sika hardener - and can be painted and sanded.

So silicone is bad for boats generally - about the only place I would consider using it is as a sealer behind plastic inspection ports.

Sikaflex comes in a number of formulations for different purposes.

Michae

Originally Posted by grayman

Iam confused P, you say " bad bad bad" but your reference seems to confirm that the sika is ok, ? what am I missing here. Mik, Iam working on the photo. graham

I apologise profusely, I'll amend it!

I read your post as "silicon" not sika!!!


Cheers,

P

Thank you all for your responses sika seems to be the go then. I will rake out a small groove as this seems to make sense and the advice on the primer will also be taken up. AD, it was you who asked for the photo, it looks to me to be NZ kauri but I will stand corrected. I assume the correct way to repair is to remove rivets and sika in the opening and then re rivet ? but Iam not sure. Apologise not necessary P but you did have me going there for a while. What ever did we do without the net. Graham

I'd first find out why it's leaking and if it's as I suspect (worn out clenches or rivets), you have a few options.

Trailer born clench built lapstake hulls survive well, but eventually the movement of the planks, especially in power craft, stretches out the fasteners in their holes or literally physically deforming them.

If this is a reasonably new occurrence, the roves or clenches can be "tightened" up again, which usually restores their watertightness.

Unfortunately, the leaking is often tolerated for a number of years, whereas the planks then begin to saw against each other, along the mating surfaces (inside the laps). This lessens the material inside the laps, furthering the leaking issue and threatening the other structural elements (ribs, stringers, etc.), because they have to pick up the loads the laps are now incapable of assisting with.

This is why finding out what and why you have leaks is important.

If you have a handful of clenches or roves that have lessened their grip, a few well placed blows with a hammer and bucking iron or rove iron will fix 'er right up. If the fasteners are in need of replacement, then you might get a season or two from the old lass with a re-pounding of the fasteners, but not much more (spent roves or clenches just die and have to be replaced).

An odd leak or two, in an otherwise sound hull, can be fixed with sick-um in a tube, but usually it's a messy job and makes proper repairs or refastening, (which will be likely in the near further in most cases) much more difficult, often with considerable damage to the planking.

I prefer polysulfide in-between plank laps, then polyurethane. Polysulfide will cure and stay stuck to wet wood, where most polyurethanes will not. Polyurethane above the LWL is fine and usually less expensive too.

I've repaired quite a few lapped hulls over the years and always use polysulfide in the seams and have never had a boat come back leaking. Chris Craft and all the other major (USA) manufactures of lapstrake craft eventually began using or switched to polysulfide too.

Polysulfide (a single part in a tube or cartridge is fine) is a sealant/adhesive, whereas most polyurethanes are adhesive/sealant. Some are better then others in each regard. I use 3M products, for no special reason other then it's widely available where I am and I have a supplier that lets me buy partial cartons of the stuff at full carton discount.

I have a 27 foot 1960 Chris Craft lapped hull here in the yard now, that has its original planking, except for the garboards. All still have the original polysulfide in their laps, and it doesn't leak, except where the replacement garboards were installed with polyurethane, 3M 5200 too, which truly sucks for me as I'll have to destroy the garboards and repair much of the ripped up rabbit, just getting that stuff off the boat.

I was hoping you (or someone else would come along and say this PAR!

Cheers
MIK

Iam sure you are right Par, as the boat is old. However, I am supprised just how good the condition of the planks are but I will now replace those rivets along where the leaks are. I am not sure why the most obvious thing to do goes past me sometimes. I appreciate your advice. Graham

Graham, to continue with advice.

As she is stored on the trailer, I would expect the boat to leak if left out of the water for some time. How bad are the leaks?

How often is she in the water and for how long?
If not often, you will be surprised how well they will take up with a few buckets of water as suggested earlier. Even quite badly built boats will stop leaking once the timber swells up. I would be trying this before anything else. If this will not stop the leaking i'd look at the following.

Is there daylight between the laps in question? If so then refastening is the way to go. A lot of nails get "over peened" or belted when installed and the nail shank bends. You wont see this when you fasten off but some years down the track as the boat is used the nail will straighten out and the joint will open.

If the gap between the laps is quite open, sometimes sand, shell grit and other crap ( I have pulled fish hooks out too!) get stuck between the laps. Simply re-fastening without trying to clean out the lap will not resolve the issue. try to get a thin feeler gauge blade in between with the fasteners removed then blow the seam out with some compressed air.

To remove the old fasteners, I use an angle grinder with a sanding disc to remove the peened section inboard and then a thin punch to push the nail outboard (backed up by a dolly outside) but be carefull not to drive the punch all the way through the hole unless it is the same size as the nail or smaller - otherwise you will be making the hole bigger.

If there is no visible lap opening, you could try and harden the nails up by placing a dolly over the peened section of the nail and tapping the nail head from outside the boat. Lots of smaller taps not big ones (or you'll bend the nail).

if you are going to place a compound between the laps, I prefer a polyurethane sealant as I know I can remove a plank that I have put it on with. I use sika -pro on my clinker new builds (that will live on a trailer) as well as on repair jobs. it is less tenacious than the sika 291, is fine in salt and fresh water and allows slightly greater joint movement than 291. Sika pro is available from any sika outlet and most hardware stores and is available in a range of colours so you can clear finish the boat if need be.

If you need any advice on fastening/s give us a yell.

regards,

AD

No sweat Graham. Now the fun begins.

Do yourself a favor and buy a good set of small bolt extractors (Easy-out is a brand in this country) and some SHARP drill bits to suit the bolt extractors.

The easiest way to remove these girls is to drill off the head of the rivet or clench, from the outside. With a punch, narrower then the shank of the rivet or clench, gently talk it into leaving the plank (beat it into the inside of the boat). You don't have to drive it far, just enough so you can grasp it with a pliers on the inside and yank it through. Don't forget the rove (a little washer sort of thing, as they sometimes stay behind, stuck in paint usually. Work gently, you can easy screw up holes (you will, but try to minimize it), because there's a bunch of them.

On a normal lightly framed hull, you'll have three clenches or rivets between frames and a regular fastener (screw or through bolt) on the frames.

Some like to try to remove the screws with a screw driver. Trust me, don't bother, 75% of them will just spin in their holes or you'll dink up the slots so bad as to make normal removal imposable. This is where the screw extractor comes in. Carefully center punch the screw head, then drill for the extractor. I install the extractor and us a "Vice Grip" to turn it out and maintain a good grip on the extractor. Most every screw will come out this way and yep, it's a pain in the butt, but the only "clean" way of doing it reliably.

Last year I replanked the bottom of a 25' lapped power cruiser. 14 planks total (out of 30), frames on 7" centers, three clenches per frame bay, except the garboard which had four. Counting screws into the ribs, that's around 2,000 fasteners that had to be removed, so take your time, you'll be at it a while.

For what it's worth, if the clenches or rivets are done, the frame fasteners are also, so don't try to save some effort or money by doing just one or the other. It's a false economy.

Also examine the fastener holes carefully. When planks have been moving around for a while, moisture gets in and usually starts rotting away the holes and weakening the frames. Fastener holes are easy to repair. Drill them out (back to good wood), glue in a dowel of similar type wood (same or nearly same density), sand flush, then hang your planks and drill for a new fastener when needed.

I think I have a more urgent problem come up so this little girl will have to wait. My mate rang late today and said that water is up over the floor in the cabin of my boat. That means a 600 km round trip and maybe having to get her out of the water. If thats the case it also means painting the hull, and a coat anti foul, its due anyway and Iam not paying to take her out now and again in a few weeks time. Its a 23ft Lacco in tip top order and I have a feeling that the leak is an old unused through hull fiitting that was weeping. At least I hope thats all it is. Geeze there is a lot to be said for those tupperware boats. Wife not happy sell the boats she says thanks everybody. Graham