Through Hull Fittings, Replacing and Glassing Over Holes

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mattnj

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I am planning on replacing all the hull fittings, the plan was to just go to ASAP supplies and speak to them about what I need, but I have just seen the plastic ones http://www.trudesignplastics.com anyone got any experience of using the plastic ones...or shall I stick with ASAP? Should I be using DZR for fittings and valves, or stainless, then bond them all together?
Makes me thing the plastic ones have to be the way forward, any thoughts?

Also, I need to get rid of 3 or 4 through hull fittings, I need them glassed over, obviously it is important to get that right! Don't know where to start in terms to the process (grinding out to start?) and the materials I need to buy to fill the holes....any pointers on this, or shall I leave this to a GRP expert?

As always, thanks, this forum is great!
 
mattnj said:
Should I be using DZR for fittings and valves, or stainless, then bond them all together?
Click to expand...

DZR, and don't bond them.

Or go for the plastic ones (proper engineering plastics like the ones you link to, not the cheap white ones in a tray at the chandlers) but I don't know much about those.

Pete
 
There are two types of plastic hull fittings that I know of, truedesign as you mention seem to have separate valves to the thru hull, and Marelon which integrate the two functions. I have replaced the four skin fittings on my 10 year old yacht with Marelon fittings, I have seen other posts on this forum in favour of truedesign, I believe either is adequate. Re filling holes, if you have any doubts I would get an insured shipwright into the loop - the consequences of getting it wrong don't bear thinking about.
 
That website seems to list valves but no through-hull fittings. The popular "plastic" ones are by Marelon. However, I had a terrible time with them and it cost me a fortune in lift-outs before I reverted to DZR. My experience doesn't seem to be representative as other people seem very pleased, and in fairness I suspect that communication issues between me and the yard added to the problem.
If you have any competence with fibreglass / epoxy, then filling-in the old holes is straightforward. You can find instructions (including grinding out) here : http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf
 
Closing off an old through fitting hole is bretty basic and simple.

Grind both sides back so get a countersink on both sides that meets about midway at around 16 degrees.

Tape some plastic over one side and build up the other with epoxy resin and 400 gram bi-directional cloth, you save yourself a bit of sanding bu adding a couple of layers of Rovings as the last layer, this will help smooth it out.

Leave the finish just below the surrounding area and fill with Micro-balloons, much easier to sand to shape later.

Do the same on the other side and your done.

Good luck and fair winds. :)
 
mattnj said:
I am planning on replacing all the hull fittings, the plan was to just go to ASAP supplies and speak to them about what I need, but I have just seen the plastic ones http://www.trudesignplastics.com anyone got any experience of using the plastic ones...or shall I stick with ASAP? Should I be using DZR for fittings and valves, or stainless, then bond them all together?
Makes me thing the plastic ones have to be the way forward, any thoughts?

Also, I need to get rid of 3 or 4 through hull fittings, I need them glassed over, obviously it is important to get that right! Don't know where to start in terms to the process (grinding out to start?) and the materials I need to buy to fill the holes....any pointers on this, or shall I leave this to a GRP expert?

As always, thanks, this forum is great!
Click to expand...

Done really properly making good old holes is quite a big job .

In essence it involves chamfering the edges from the outside at a fairly shallow angle 1:12 IIRC. This make a huge wound in your otherwise sound grp and gelcoat.

This is patched with layers of glass cloth starting with one the matches the outside diameter of the prepared area and adding progressively smaller patches to make up the original thickness ending with a piece that matches the internal diameter of the hole.

( with small holes a patch can be made up first and applied in one go)

Finally you can put a couple of layers over the whole area internally although if the above is done properly not absolutely essential.

You will find all the details and full instructions on the Wessex Resins website. CW with advice on the materials, fillers etc to use

Good luck ... I did a 2" diameter hole a couple of years ago. Frightening having to start by grinding out such a large area ... but thats the recommended way whatever shortcuts might be suggested.
 
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mattnj said:
...

Also, I need to get rid of 3 or 4 through hull fittings, I need them glassed over, obviously it is important to get that right! Don't know where to start in terms to the process (grinding out to start?) and the materials I need to buy to fill the holes....any pointers on this, or shall I leave this to a GRP expert?...
Click to expand...

The West system website has many useful 'how to' articles. This one http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf has exactly what you need in section 4. But it involves quite a bit of expertise, preparation and materials, so it's possible that a boatyard would do the job for not a lot more than you could.

Dang, just realised that the same URL had already been posted by the time I'd written my post.
 
I went with these from www.shakewell.info no skin fitting necessary, bonds directly to the hull

WP_000253.jpg
 
jdc said:
The West system website has many useful 'how to' articles. This one http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf has exactly what you need in section 4. But it involves quite a bit of expertise, preparation and materials, so it's possible that a boatyard would do the job for not a lot more than you could.

Dang, just realised that the same URL had already been posted by the time I'd written my post.
Click to expand...

Thanks! Read that, one for the boatyard me thinks!
 
I replaced with TrueDesign, The plastic valve is physicaly larger than a DZR valve, probably to have the mechanical strength. This needs to be taken into account if you do not have much room. Do a dry fit first to see if everything fits into place as it should. Mine have been in for three years and I am very happy.
 
KellysEye said:
not made of plastic, they are a nix of nylon and GRP
Click to expand...

You know what the "P" in GRP stands for, right? And nylon is a thermoplastic.

Doesn't mean there's anything wrong with Marelon valves, of course. Glass-filled nylon is a perfectly good engineering material, and after all most of us are floating around in plastic boats.

Pete
 
+1 for Marelon Forespar, replaced all originals on previous boat, easy to fit and no issues with handle sticking.

Also had to repair the hull where I ended up with a big ugly hole after a slightly clumsy removel of an original Blakes.
West System epoxy was really easy to work with after correctly grinding the hole to a shallow taper and preparing the surface. Multiple discs of decreasing size as described earlier.

To reassure myself of the strenght of the repair I also made a really quick lay up at home with only 5 layers of cloth and resin (11 layers of cloth on the boat repair), and didn't take as much care with the squeeze/bond either, leaving some bubbles and wrinkles. "Testing" the lay up at home with a 2lb club hammer, I couldn't break it and only produced some surface damage to the resin so I'm pretty confident the repair is likely to outlast the rest of the original hull.

Andy
 
I replaced mine with TruDesign fittings- very easy DIY job and they're a pleasure to use. No more arm wrestle to operate the bigger sizes.

John
 
My experience was gained on GRP cars esp Lotus and small repairs to sailing dinghys but in addition to comments of building up glass fibre layers you also need to consider outside gel coat and on inside finish with flow coat.

I do gel coat by troweling it on the shape with cling film over. My understanding is cling film helps setting of gel coat.

If inside is not visible you can think about overlaying area to strengthen it.

When doing cars I was unhappy strength wise if my repair was the same thickness as original eg repairing crashed torn GRP.

I replaced all my through hull fitting with ones from ASAP last spring. I posted various questions and received some good advice. I also posted a wrap up post on lessons learnt. You may find it useful to use search facility as many were doing similar work during winter lift out and there were many good posts including easiest way to cut out old fittings, best Locktite to use ( some sets almost instantly) and source of short adjustables for access.
 
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VicS said:
In essence it involves chamfering the edges from the outside at a fairly shallow angle 1:12 IIRC. This make a huge wound in your otherwise sound grp and gelcoat...
Click to expand...

Just checking I understand this fully: if the thickness of the GRP is 20mm, this means chamfering a circle of radius 240mm around the original hole?

How on earth can you do it evenly?
 
Its quite easy really, did it when i was removing and closing off all my old skin fittings, draw a big circle around the hole and profile through the cloth, like planing a shape into plywood, just follow the laminations down until everythings symmetrical, same with fibreglass, just follow down through the strata of matt and rovings until its relatively even around the hole.

On my own boat I've never gone 12:1 especially in the engine room when i was closing off drains and engine inlets as it wasn't physically possible to go out very far from the hole and not hit a bearer or locker structure also contrary to popular belief my Centaur's hull wasn't that thick around keel stubs and engine area.

Some marine ply hatch surrounds i made for my boat that should explain the above:

19082011362.jpg
 
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