Through hulls again.

[noswellplease]

I've been busy replacing and upgrading various items on my old boat and have all the cusions and seats removed to assist new wiring and all the rest. I'm wondering while I'm at it, is this the time to replace all the through hulls and maybe sea cocks. Problem is I dont know when they were last replaced if ever.
The through hull has been glassed over on the outside but appears to be in reasonable condition when the glass scratched off a bit. There are six through hulls involved. Also how long might I expect a through hull take to remove. I suppose an anglegrinder is considered a no no for the job.
I plan to hold on to the boat for a few years more at least so would like to feel good about the skin fittings and keeping water out. Any thoughts appreciated Russ

 

[damo]

I have replaced most of mine over the last couple of years, as they became accessible while doing other jobs. They were all bronze I think, and seemed to be in good nick, apart from the trashing they got during removal!

If they have a couple of lugs inside the outer part, you can get something in to stop it from turning while you get the inner nut off. If the nut is immovable then I cut down through the threads and nut with a thin angle grinder blade, pop off the 2 halves of the nut, pinch the cut threaded section together, and then it usually drops out easily.

On all the ones I have done I glassed on substantial backing pads (flimsy bits of untreated ply before /forums/images/graemlins/frown.gif ) and epoxied the surface of the new hole.

 

[noswellplease]

damo....what did you use for backing pads, can you get pads with the fittings when you buy them or do you just make them up out of teak or something else...Russ

 

[damo]

I used ply with chamfered edges, then made up some resin putty to bed it down on and make an even contact with the curvature of the hull. When that had gone off I glassed over it. After cutting through it from the outside I epoxied the exposed surface.

In theory ply isn't the best, in case it gets wet, but the old stuff was wet and had lasted a good few years. I reckon teak etc would also do the job, except that you would need to de-oil the surface first. Something synthetic like tufnol would be best of all IMO

 

[roly_voya]

How old is the boat? I have veriouse blake seacocks that are 30yrs old and still perfect and now of many case of true bronze fittings lasting much longer. You might want to carfully check ball valves which often are not bronze but the actual skin fitting should be fine as long as its zinc free.

 

[damo]

The seacocks were nearly 30 yrs old, and since several other things on the boat were dodgy installations, I decided to change the lot for piece of mind. Several backing pads were sodden where the through hulls were weeping, and 2 large gate valve wheels were almost inaccessible. Everything has now been changed to ball valves, and 3 redundant thruhulls blanked off.

While I was at it I also glassed on 2 "spare" backing pads while the engine was out, just in case I ever do an offshore race, so I can bring the cockpit drain requirements up to spec.

 

[noswellplease]

The boat has cellebrated its 38th birthday and most of its life spent in Holland. I think the thru hulls are good but how can one be fully sure and it only takes one iffy one to cause big trouble. It might be a small price to pay in the end for peace of mind.

 

[oldsaltoz]

We removed all the thru' hull fittings in a 28 year old yacht last year, all original and all in good condition, made of admiralty bronze, all had timber backing pads; every pad showed signs of failure due to moisture.

Refitted them all with fibreglass backing to spread the load and the seal area made from resin and Micro-fibres, this provided a neat flat seal area. The hole is 4 mm oversize to accommodate a gap for sealant.

We have used this method for over 30 years on many boats and never had a problem, despite the fact that some have been impacted.

When God grows a timber that is waterproof and strong enough I might consider trying a bit, other that I will stay well clear of timber below the water line, and avoid it where possible above the waterline.

Hope this helps.

Avagoodweekend......