Repairing a hole in the cockpit floor

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SteveSarabande

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The last owner fitted a Vetus Mushroom vent through the cockpit floor. I presume it was done to ventilate the inboard, but it is more likely to flood the boat when the self draining cockpit takes a wave. There is a photo here, http://www.flickr.com/photos/75351251@N03/8365176240/in/set-72157632414296285

I am guessing the hole left behind is going to be around 4". I have access behind it and could fit a thick piece of plywood below trhe whole, in the engine bay.

I want to know how to fill the hole so that the first person to step on it doesn't fall through. There is a wooden grating that will sort of cover the area of the hole, the cockpit sole is all painted fibreglass, not sure how thick yet, but it's an old Sabre27 so probably pretty substantial.

I could bolt through the deck to a large plywood pad at the back, then just fill the hole with another circle of plywood. Then paint over the whole lot, but is there a better way.

Any ideas?
 
Stevev2 said:
The last owner fitted a Vetus Mushroom vent through the cockpit floor. I presume it was done to ventilate the inboard, but it is more likely to flood the boat when the self draining cockpit takes a wave. There is a photo here, http://www.flickr.com/photos/75351251@N03/8365176240/in/set-72157632414296285

I am guessing the hole left behind is going to be around 4". I have access behind it and could fit a thick piece of plywood below trhe whole, in the engine bay.

I want to know how to fill the hole so that the first person to step on it doesn't fall through. There is a wooden grating that will sort of cover the area of the hole, the cockpit sole is all painted fibreglass, not sure how thick yet, but it's an old Sabre27 so probably pretty substantial.

I could bolt through the deck to a large plywood pad at the back, then just fill the hole with another circle of plywood. Then paint over the whole lot, but is there a better way.

Any ideas?
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If talking about fibreglass, chamfer edge of hole on outside, blank internal, progressively fill with CSM & resin, finish with gelcoat with added styrene.
 
Easiest thing that comes to mind is to fit one of those aluminium table sockets, it will cover the hole, can be sealed easily, and if you want to you could even use it for a table...
 
Filling holes seems to be the standard first fibreglassing job people undertake, so the Internet is awash with good instructions on how to do it. That's what I'd do, not fanny around bolting things to it.

My previous owner had cut a 6" hole in the side of the cockpit footwell, in order to more easily stow his tiny fenders (better suited to a dinghy) in the quarter berth. I reckon that beats your mushroom for daft modifications :). I read up on fibreglassing, bought the bits from East Coast Supplies, and had it all done in an afternoon. The ex-hole is barely noticeable, only because the new gelcoat isn't sun-yellowed like the old.

Pete
 
If it were my boat I would be filling the hole with fibreglass. Of course you can't do f/g work so well when it is cold however some heating might help. I think polyester resin should be fine for the job. With the advantage that you can put more hardener in to accelerate hardening in cold weather. Yes epoxy is better but does deteriorate in sun and needs more warmth to cure.
You need a backing of some sort to build the fibreglass up on. If you can access under neath then a plastic bag filled with sand pressed under the hole or a piece of ply covered in cling wrap pressed against the hole. If you can't access under neath then you need a piece of ply or similar which can be slipped through the hole and pulled up under the hole. Small gaps at the side of the board will not matter much or can be filled with chewing gum or equivalent.
As said chamfer the upper outside edges of the hole so the f/g plug will not push through the hole with weight.
Lay up lots of layers of fibreglass with resin. Use chop strand mat for polyester resin but not for epoxy. Use cloth or woven rovings for epoxy (or polyester). When you have filled the hole let the resin harden before you smooth it off. Or use more resin with a filler like microballons or even talc powder. Finally paint over it. good luck olewill
 
William_H said:
If it were my boat I would be filling the hole with fibreglass. Of course you can't do f/g work so well when it is cold however some heating might help. I think polyester resin should be fine for the job.
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I rebuilt KS's aft deck, after cutting out the rotten core, at this time of year. Just rigged up a sort of tent around the area in question, with an electric fan heater in it. A bit of a faff, but not too bad.

Where I'm working on the new boat's mast, there are a couple of boats presumably having epoxy work done to keels or bottoms. They have plastic sheeting draped around them and big glowing heaters inside the "tent", running 24/7.

Pete
 
Thanks everyone. Fibreglass work is new to me, hence the question. I see now that chamfering the top will stop it pushing through.

I will wait for warmer weather and give it a go.

Cheers
 
I would probably fit a flush fitting inspection cover, various sizes available. I have one inset into a larger wooden inspection board that is sealed and scewed down. Works well for a quick peek ;)

Force4 item number 850007 4" £5.95
850008 6" £6.95 They do larger sizes!
 
Talulah said:
You don't really need to do anything. The Vetus Mushroom vent can be closed. There is a knob on the underside to turn which will seal it shut.
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Is it then fully waterproof.? Even with the cockpit full of water. It is on the cockpit floor.

There is really no need for it, it only ventilates the engine bay and that already has plenty of air flow via small holes to the lockers
 
ReefMagnet said:
Replace the vent with an inspection port of appropriate size? It won't leak then.
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Agreed.
My cockpit sides had redundant stainless brackets bolted and bonded to the fibreglass. Removing them also took off the gelcoat down to the lay.
I cut out the damage and fitted plastic inspection ports which let in useful light in the space behind, in my case the heads and galley (centre-cockpit).
 
Stevev2 said:
Thanks everyone. Fibreglass work is new to me, hence the question. I see now that chamfering the top will stop it pushing through.

I will wait for warmer weather and give it a go.

Cheers
Click to expand...

I was in a similar position as yourself. When you remove the airvent, if it is a deep enough hole cut a piece of ply to semi fill it first. Then paint with epoxy resin and straight away start to lay the glass fibre, layer by layer. You can get it cheap enough at an decent car repair shop. Lower price than the swindelry.Don't forget to do both sides.

Good luck

Peter
 
rivonia said:
Then paint with epoxy resin and straight away start to lay the glass fibre, layer by layer. You can get it cheap enough at an decent car repair shop.
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Do car shops sell woven cloth, then? I've only seen chopped mat in connection with cars, which is not suitable for use with epoxy. The strands are held together with a binder that dissolves in the styrene in polyester resin - but epoxy doesn't contain styrene.

(Not that I think epoxy is needed for this repair, polyester and mat (from a car shop if you like, though I buy it from a fibreglass supplier online) will be fine.)

Pete
 
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