Leaking Lewmar hatch

[matt1]

I've got several of these new "frameless" flush hatches, one of which leaks when solid water lands on it. At the fwd and aft ends its nice and tight against the seals (held by the hinges and handles) and to be fair it seems tight along its sides too (despite only relying on the stiffness of the acrylic to hold it tight) However, on investigation it looks like it's leaking from the sides, and is probably flexing when heavy waves land on it (it doesn't leak with spray or rain / hose). There is no adjustment to be made in the hinges (or handles that I can see). The annoying thing is we have only ever opened this hatch a couple of times, so I am thinking of just putting silicone sealant over the rubber seals to permanently seal it, but realise this would render it inoperable (which I don't really want to do). Lots of people here rave about Butyl tape. Is that an alternative, to put that between the rubber seals and the hatch? Presumably if that worked it could still be opened if required?

 

[Deleted member 36384]

Interesting idea as a solution, but sealant as you say defeats the purpose of the hatch. I would at least try the tape first. I would recommend Scapa 3507 bedding tape, which is a non mastic tape that has good tenacity i.e. it returns to its original shape after compression, also designed for items that need to be removed. I have used this around aluminium window frames with great success. It needs to be compressed by 30% to develop sealing ability and is available in different widths and thicknesses.

Seals-Scapa 3507

Regarding your original hatch. It could be that the seals have failed by softening and losing some of their their elasticity and tenacity, maybe due to grease from hands, suncream, where people may leverage the sides as they exit the hatch. Elastomers can degrade, or even could be damaged, worth checking if they can be replaced first.

 

[matt1]

Interesting idea as a solution, but sealant as you say defeats the purpose of the hatch. I would at least try the tape first. I would recommend Scapa 3507 bedding tape, which is a non mastic tape that has good tenacity i.e. it returns to its original shape after compression, also designed for items that need to be removed. I have used this around aluminium window frames with great success. It needs to be compressed by 30% to develop sealing ability and is available in different widths and thicknesses.

Seals-Scapa 3507

Regarding your original hatch. It could be that the seals have failed by softening and losing some of their their elasticity and tenacity, maybe due to grease from hands, suncream, where people may leverage the sides as they exit the hatch. Elastomers can degrade, or even could be damaged, worth checking if they can be replaced first.

Thanks for the recommendation on the tape. I’ve not used this kind of stuff before, so it’s useful to have a brand / type recommended.

The seals are only 3 years old and look in good condition and well adhered you the frame. The hatch has only open a few times and isn’t used as access.

 

[KAM]

Have you checked the mounting flange to deck. I find I have to touch up the sealant every few years. It's probably either the differential expansion or the deck flexing.

 

[matt1]

I haven’t checked that but am aware that the powder coating is fairly notorious and has a history of failing and obviously this causes issues with the sealant between deck and flange. I’m pretty sure it’s through the seals though as I can see the acrylic flex and when I opened it there were traces of salt on the rubber seals

I’ll take a look at the join to the deck though as potentially it could be that