how would you seal this access hole from the weather ?

[simonfraser]

just cut this under a lid at the stern for access to a hydraulic pump
it is covered by a deck lid on a hinge, but this is not water tight, so some rainwater will run to the newly cut hole

if i ever need access again the new cover needs to come off, not very often i hope
by the looks of it i have been the first one in 20 years

so could just screw a panel on, and sikkaflex it, or bathroom silicone it ?

oops, yes i forgot to add the pic, been a long day !

 

[Ceirwan]

A picture would help.

 

[Deleted member 36384]

You need to post your picture.

Whale, for example make water tight deck covers, round lids with a flange base. https://www.asap-supplies.com/whale...ka21Hw6IQbr-7fgLifzXJIoS-RJXgT_saAv1UEALw_wcB

 

[geem]

Having never had much success with puropse built access panels that were supposed to be waterproof I would opt for a grp panel cut to size and bolted with a set of glassed in s/s bolts. You could make up the lids by making you own grp panel about 8-10mm thick. Bed the lid on the rubber inpregnated cork gasket you can buy and use silicon on the gasket. This is our water tank set up and it never leaks. If you need to remove in the future the silicon will come off easily.

 

[Poignard]

How about something like this? https://www.yachtchandlers.co.uk/acatalog/Inspection-Hatch-Sturdy-Anti-Slip-NYC7650.html If you can find the right size.

Although you may not think you will ever need quick access to it, one day you may need to do so, and in a in a hurry.

 

[pvb]

Another vote for a simple GRP panel set on a rubber gasket, with some silicone sealant added. I'd probably hold it down with stainless selftappers or machine screws.

 

[simonfraser]

Another vote for a simple GRP panel set on a rubber gasket, with some silicone sealant added. I'd probably hold it down with stainless selftappers or machine screws.

k, you guys recon i need a rubber gasket AND silicone ?
just silicone is not going to work ?
easy to do the rubber gasket, just never done this b4.

extremely unlikely to need access in a hurry.

 

[PetiteFleur]

would also use a simple grp panel, overlapping about 1" all round, with a rubber gasket - I've used the 'W' section for window sealing in similar situations. Easily bought from the likes of B&Q or Lidle/Aldi. I'd use two strips all round with stainless self tappers about every3".

 

[geem]

k, you guys recon i need a rubber gasket AND silicone ?
just silicone is not going to work ?
easy to do the rubber gasket, just never done this b4.

extremely unlikely to need access in a hurry.

Quite often grp sections on a boat are not totaly flat so the gasket material has to take up quite a lot of thickness variation. You could opt for gasket only but since silicon is so easily removed it just makes sense to go belt and braces rather than having to do the job twice.

 

[simonfraser]

Quite often grp sections on a boat are not totaly flat so the gasket material has to take up quite a lot of thickness variation. You could opt for gasket only but since silicon is so easily removed it just makes sense to go belt and braces rather than having to do the job twice.

Great, tnx all. Job for Tuesday.

 

[Ceirwan]

since silicon is so easily removed

Silicone is probably the hardest thing to completely remove that you can use when sealing any piece of deck hardware short of some form of permanent adhesive.

 

[johnalison]

My experience of gaskets is that they tend to leak eventually. The most watertight solution I can think of would be to built up a lip on the hole and put a fibreglass lid over it, with a gasket inside the lid to bear on the edge of the lip.

 

[Poignard]

My experience of gaskets is that they tend to leak eventually. The most watertight solution I can think of would be to built up a lip on the hole and put a fibreglass lid over it, with a gasket inside the lid to bear on the edge of the lip.

Good idea.

 

[prv]

My experience of gaskets is that they tend to leak eventually.

I hope not or else my diesel tank is going to make a mess. No sign of any leaks so far, since I took an angle grinder to it and then fitted a plate similar to the designs being suggested here (except my tank plate is stainless on stainless rather than GRP on GRP).

For a once-in-20-years job I suppose he could use white sikaflex 291. Run a thin knife blade around under it to cut the sika when the time comes, then clean off the remains from both sides with a bare new stanley blade pushed like a plane. Worked fine for the plotter pod I stuck down with Sika and then took up again a few years later when fitting a new plotter that didn't fit in the old hole.

The most watertight solution I can think of would be to built up a lip on the hole and put a fibreglass lid over it, with a gasket inside the lid to bear on the edge of the lip.

Would be a fair bit of work for someone probably new to fibreglassing though, and protrude obnoxiously into the locker versus a flat panel glued or bolted direct to the bottom.

Pete

 

[rogerthebodger]

Another vote for a simple GRP panel set on a rubber gasket, with some silicone sealant added. I'd probably hold it down with stainless selftappers or machine screws.

I agree with a simple bolt on panel but I would use a sheet of HDPE about 8 to 10 mm thick.

I have used HDPE on both GRP and steel tanks with neoprene foam gaskets.

 

[lw395]

I did something similar once and fell for the 'silicone is easy to break' idea that people keep trotting out.
I reckon a 1cm wide bead of silicone around a 40cm square locker bin was resisting a good couple of hundred kg force. In the end I had to make a tool to get in and cut the silicone.
It's useful to have some sort of gasket in there so that the bead of silicone is a few mm thick, not flattened to zero. Rubber spacers at intervals works quite well.

 

[johnalison]

Would be a fair bit of work for someone probably new to fibreglassing though, and protrude obnoxiously into the locker versus a flat panel glued or bolted direct to the bottom.

Pete

It need only be an inch or less.

 

[Fr J Hackett]

Glass some nuts on the underside run some butyl tape around the opening then bolt down a lid use perspex or make one from GRP.

 

[geem]

My experience of gaskets is that they tend to leak eventually. The most watertight solution I can think of would be to built up a lip on the hole and put a fibreglass lid over it, with a gasket inside the lid to bear on the edge of the lip.

Both my fuel tank and water tank have lids as I described in my post and as I have suggested the OP could adopt. Neither tanks leak. The system has been in use like this for 39years! The tank walls are 15mm thick GRP the lids are the same. The lids use 10mm s/s bolts glassed to the underside of the tank. Both tanks use the rubber inpregnated cork gasket with a thin layer of silicon on the water tank and CT1 on the fuel tank. It works perfectly. Why do you think this would leak?