Fitting new portlight / hatch

[JeremyF]

This weekend I plan to fit an additional portlight into the side of the cockpit to let more light into an otherwise dark aft cabin. Ive chartered one with this mod., and it makes a huge difference.

The question I have is whether to put washers between the portlight and cockpit to allow for the Silkaflex to have a couple of mm space to go. My thinking is that if there is no spacer tyhen the Silkaflex will get totally sqeezed out when fastened down.

Thanks in advance

Jeremy Flynn

www.yacht-goldeneye.co.uk
New pics 11.02.02

 

[Guest]

Jeremy,
I doubt you would remove all the sikaflex but an option that would avoid the hard spots at the washer locations would be to apply sealant and tighten until a mil or two is left,tidy off the margin and allow sika to cure abit then tighten onto ''Flexible gasket'' you have created with sika.
Just an idea

 

[ccscott49]

Doug, that is the correct way to do it! Reccommended by sikaflex themselves.

 

[AndrewB]

With a load of sealant its not that easy judging when you've tightened to 2mm. I'm doing my portlights at present, first fixing dry, then marking on the bolts or counting the turns to where they'll give the correct clearance.

Fully tightening after about ½ hour, when sealant has partly but not completely gone off.

 

[ccscott49]

Good idea, I wish people wouldn't use so much sealant, it only has to be disposewd of afterwards!

 

[JeremyF]

Thanks everyone for another high-quality response.

So, its no washers, apply thin skim to entire area, then tighten lightly to 2mm or so, allow to harden off a bit, then tighten down.

Simple when you know!

Jeremy Flynn

www.yacht-goldeneye.co.uk
New pics 11.02.02

 

[LeonF]

Just about to do mine which were replaced before I bought the boat (last year) but have developed nasty leaks. They looked well done too! The Sika literature suggests using rubber spacers but I'm not sure where to get them from and whether one leaves them or puts them on the edge then removes them and fills the gap. Also remember to use Sikaflex 295UV. It is much cheaper to get it from Marine and Industrial Sealants in Norwich rather than order it from a chandlers. It is unlikely that you would find it on the shelf.

L.A.R.Ferguson

 

[30boat]

When you tighten the screws make sure they don't turn oterwise you'll break the seal around them .

 

[MedMan]

I wouldn't use washers. An extra thickness of sealant somewhere in mid air between the hull and the flange is not doing anyone any good other than water proofing the gap that you created with the washers! True, without washers, most of the sikaflex will be squeezed out, but the bit that remains is the bit with a job to do - it fills the tiny undulations and imperfections between the two surfaces. Also, most hatches have a groove milled out of the under side of the flange which will form a bead of sealant of a decent cross section that cannot be squeezed out.

A cordless drill/screwdriver with a variable torque control makes the whole job much easier. Set it on 1 (lowest torque) and go round all the nuts whilst the first mate holds the bolts firm on the other side. Now rack up to torque setting 2 and go round them all again. Repeat until the whole assemply is rock solid. Leave until the sikaflex is touch dry on the surface and run a blunt knife (an old dinner knife is fine) vertically around the flange to separate the extruded bead from the frame. (Don't run the knife horizontally to separate the bead from the hull or it may disturb the sealant under the flange) Leave until the next day and remove the excess sealant with the same blunt knife.

I used to be in favour of the tighten loosly to today and pull it up even tighter tomorrow, but I am not any more. However hard you (or the first mate) tries to hold the bolt firmly when you put on that final torque, at least one of the bolts will turn and destroy the seal around it that was perfect until you messed about with it.

Have fun.

David