Couple of questions.

[Bunny]

Morning folks. I have recently purchased my first grp boat and have a couple queries. It is going on the hard soon as i have two seized sea cocks and i am going to antifoul as well. Firstly has anyone ever freed a secock with a hot air gun, as access is quite tight for a complete removal with a wrench. Secondly, as i dont know what antifoul is on now, can i just remove the loose bits, primer the bare bits, the go over it all with new antifoul. Do different types react with each other? It is a 32 foot mobo on the south east coast. Thanks in anticipation, Bob.

 

[Twister_Ken]

Freeing seacocks - stick a drift up the hole from outside and give it a few light taps with a hammer. Often frees things up enough to shift. Not sure how you'd use a hot air gun - don't go melting any plastic pipes. I'd soak them in freeing oil for an hour or two before attempting to free them. If you can't get a wrench to them, you can get quite creative getting a socket onto them, using various extension pieces and universal drives.

Antifoul - hard question. You can't overcoat a one pack onto a two pack, so if that's what you'e got on (ask previous owner?) you'll have to prime over the lot. Otherwise, scrape off loose stuff, prime those patches and slap on more jollop.

 

[boatbuilder]

What sort of seacocks are they, some are redeemable, some just need chucking in the skip.
Pics would help. /forums/images/graemlins/smile.gif

 

[Topcat47]

It rather depends upon the design.

Blakes, apply penetrating oil, leave for a bit, pour on hot water (it'll drain to the bilge) then drift in from outside the hull. The extension bar from a socket set works, hit with increasing force until it pops out. Lap in with grinding paste. Re-grease with Blakes seacock grease (no point in you repeating my mistakes with other greases) then Bob's your mother's brother.

Ballcock, remove and replace with new. Too cheap to fiddle about with.

Gate valves, remove and replace with ball valves....they work better and see above.

I've yet to find an antifouling that won't go on over another, but hey.....it's not as if I've tried them all.

 

[Bunny]

Hi, they are the ball type, not the tapered ones.Im probably cutching at the proverbial but i am combining the lift out to co incide with a weeks shore based course, so time will be limited and was kinda hoping that half an hour with a heat gun would leave more time for the bottom. As for photos, ive only just learnt how to swiitch this bloomin thing on!cheers, Bob /forums/images/graemlins/confused.gif

 

[Topcat47]

Sod's law of the sea says if you've five minutes to do a job it'l take five hours.....if you've five hours it'll take five minutes.

With Ball Valves you have to be careful with the hull pentrations, unscrewing the valve can move the hull fitting and cause a leak. My hull fittings have a protusion inside to hold them still, (which makes it a 2-man job) but even this is no guarantee.

OlDSALTOZ's method for replacing hull fittings bears repeating here......clean hull inside and out, slap lots of marine sealant round the fitting.....install hand tight.....pissoff for a day or so....return to tighten up fitting and connect ballcock, using more sealant.

 

[Topcat47]

Here's his post, verbatim....

"Every boat I ever owned that had a timber backing on any thru hull was removed, the hull was then glassed to give a flat area for the thru hull valve to seal on.

Ply was fitted because it bends to the hull shape and provides a flat seal area the same as the adding of glass above does, but costs less.

Problem with ply is that it can get soft, then tension is lost resulting in a leak, this lets more water into the timber and it gets softer, you know what happens next.

Replacing a thru hull fitting is not rocket science, remove old, check hole is clean and not damaged, insert new or refurbished thru hull leaving about an inch gap and apply a suitable sealant to the outer edge of the hole and around the inside of the flange on the fitting. Now from inside pull the fitting so the outer flange meets the hull, add a little sealant around the base and drop on a flat washer, plastic or neoprene is good, tighten till finger tight then add another half turn. From outside, wipe off any sealant that has squeezed out and check the alignment is even around the flange and that it's still 1 or 2 mm clear of the hull. Go home and come back in a day or two and tighten the fitting, antifoul and get back in and have some fun.

Avagoodweekend......"

 

[Bunny]

Thanks to all who replied. This may not be as easy as i had hoped. cheers, Bob

 

[john_morris_uk]

I don't believe that there is an ongoing problem with using ply as backing for through hulls. Good quality Marine Ply, painted and properly bedded is extremely robust.

If you give it two coats of epoxy I suspect that it will last the lifetime of the boat.

All our through hulls have ply backing pads and I have total confidence in them.

I don't know why people spread rumours of disaster where none is likely!

 

[Topcat47]

The marine ply backing pads on my boat have been there for forty years and not gone soft. I see no rteason the change mine, however, Oldsaltoz is a professiot hnal boatbuilder with much more experience than I and what he says seems sensible too. I'd take his advice before mine on the subject, were I anyone other than me.

 

[john_morris_uk]

Hmm - well I am not trying to criticise a 'professional boat builder', but I stand by what I say. I have worked with professional boat builders of all sorts of shapes and opinions. Some are good and some are bad. Some of their help and advice has been very helpful. Some has been barking mad and I have ignored it.

Like many many others, my boat was built with ply backing pads on the the through hulls and I just don't see a problem with them now or at any time in the near future. They were fitted by professional boat builders as well.

Perhaps Oldsaltoz has seen some poor quality pads put on by amateur boat builders?

Whatever the truth of this, I stand by my backing for the (good quality) plywood backing... In fact I will suggest that ply is better than a hardwood pad as it is less likely to split.