Fitting Forespar Marelon Seacocks

[superheat6k]

I have bought some Forespar Marelon seacocks for my raw water inlets. ASAP supplied them complete with a mushroom through hull, but there is no retaining nut for the through hull.

The valves have three mounted holes 120 degree spaced around the periphery with a flat face as well as the 1 1/4" BSPF screw thread..

What way would others fit these (I will seal with sikaflex) ...

1 Adjust the length of the through hull to suit the hull thickness with say 1.5 - 2 turns shy of the bottom of the seacock female thread, then simply wind up damn tight direct to the hull.

2 As 1 but with a marine ply spacer plate say ~ 100mm diameter (valve size is 1 1/4" bore, so OD ~ 65mm ?

3 As 1 but also through bolted through the peripheral holes ?

4 As 2 but also through bolted ?

Thanks all

 

[VicS]

I have bought some Forespar Marelon seacocks for my raw water inlets. ASAP supplied them complete with a mushroom through hull, but there is no retaining nut for the through hull.

The valves have three mounted holes 120 degree spaced around the periphery with a flat face as well as the 1 1/4" BSPF screw thread..

What way would others fit these (I will seal with sikaflex) ...

1 Adjust the length of the through hull to suit the hull thickness with say 1.5 - 2 turns shy of the bottom of the seacock female thread, then simply wind up damn tight direct to the hull.

2 As 1 but with a marine ply spacer plate say ~ 100mm diameter (valve size is 1 1/4" bore, so OD ~ 65mm ?

3 As 1 but also through bolted through the peripheral holes ?

4 As 2 but also through bolted ?

Thanks all

I would fit them in the way Forespar show in the video on their website ........... You dont through bolt them but you do need a ply spacer . They show you how to adjust the length.

 

[yoda]

https://www.youtube.com/watch?v=bHNNVrGPeew

Useful video here

Yoda

 

[David2452]

All the ones I have fitted have been done as per the Forespar install protocol which is quite specific and detailed in the videos mentioned, with the exception that I have of late used 8mm GRP sheet instead of ply. One really important part is the dry fit which goes to the final position of the valve lever and or angled hosetail, the through hull must be inserted in the same position and not allowed to rotate during final fit. The most stressful part on the first few was cutting down the through hull to length, I use a multi tool with wide wood blade on slowest setting.

 

[Dipper]

I fitted one of these last season but I got it slightly wrong. I had left the internal part of the skin fitting a millimetre too long and it leaked. The seacock hadn't bedded down fully. Because it was on a fairly thick ply pad, the leak stopped completely after a week or so, presumably because the pad had swollen.

Unless the interior of your hull is smooth and flat, I would fit a ply backing pad. It certainly helped me!

Cut the skin fitting to length and fix it in place (at the correct orientation for the handle) with Sikaflex.

You aren't supposed to use sealant on the thread because it makes removal difficult. They are designed to be removed afloat although you have to dive under the boat and put the supplied plug in the skin fitting first.

Screw the seacock on by hand. It's only supposed to be hand tight. You can use a sealant on the base and this is what I have done second time round.

If you use a backing pad then you can screw three self tappers through the peripheral holes and into the pad for peace of mind. Drill through the holes first as they don't go all the way through. You don't need these screws and you certainly don't need through bolts. The seacock itself acts as the backing nut and it is a perfectly safe arrangement despite some doubts expressed by others on this forum in the past.

Good luck.

Edit: I would have been the first to reply but got called away halfway through typing my reply. I see others have linked to a useful video.

 

[superheat6k]

Thanks - most detail is explained, in the video except the outer screw holes. I did note the bit about not having further holes in the hull (which is unlike Blakes plug valves).

I assume I just use three hefty ss wood screws that only go into the backing plate, or is this unnecessary. The diagram is a bit vague on this and in the video he mentions using screws but doesn't show these being affixed. If they were not needed why do Forespar provide them ?

Sorry to labour the point but my first time using these plastic valves and I want to get it right.

Thanks Dipper my reply crossed with yours. I will likely omit the extra screws.

 

[VicS]

Thanks - most detail is explained, in the video except the outer screw holes. I did note the bit about not having further holes in the hull (which is unlike Blakes plug valves).

I assume I just use three hefty ss wood screws that only go into the backing plate, or is this unnecessary. The diagram is a bit vague on this and in the video he mentions using screws but doesn't show these being affixed. If they were not needed why do Forespar provide them ?

Sorry to labour the point but my first time using these plastic valves and I want to get it right.

Thanks Dipper my reply crossed with yours. I will likely omit the extra screws.

In written instructions they do say that the flange should be screwed to the backing pad.

The pad will be pretty securely stuck to the inside of the hull by the adhesive sealant recommended but the valve body is not quite so securely stuck to the backing pad. The screws will anchor it securely to the pad.

http://www.forespar.com/products/bo...e-mounting-seacock-thru-hull.shtml#fragment-2

and

http://www.forespar.com/products/bo...e-mounting-seacock-thru-hull.shtml#fragment-7

 

[Dipper]

Thanks Dipper my reply crossed with yours. I will likely omit the extra screws.

Sorry. I should have said. I did use the three screws. They just add an extra level of security. One set of instructions that I saw said they weren't necessary. but I see Vic's link says to use them.