Thread: Inspection ports.

Glues set hard and with flex in a panel will crack and the seal is then damaged , with silicon sealers the material when cured stays flexible, so that flexing in the panel unless it is ridiculously excessive will not break the seal.


All things being equal , i would use SIKA FLEX for seating inspection ports.

Jeff
vk4

Yep, agree with what Jeff said. I use a flexible adhesive sealant like sikaflex but there are other polysulphide sealants that are probably just as good and cheaper.

A flexible sealant will also make removing/replacing easier in the future if you can get a sharp knife in to cut through the goo.

Personally not a fan of silicone sealant on boats.

Thanks Jeff and Gizzle.

I had no trouble finding Sikaflex. Up to €11 differnce between four different boat/yatch suppliers .

You say you're not a fan of silicone sealant Gizzle. If you don't mind me asking, what's the alternative ?

Cheers, Kev.

No worries Kev.

I’m not a fan of silicone type sealants because they can not be painted, so if you accidently get some where you don’t want it you have to wipe it off but there is probably still some residue on the surface than is difficult to remove especially when cured. Also I find that silicone is much softer and prone to damage.

Polysulphide sealant (like sikaflex) is the way to go, for clean-up after fitting use baby-wipes, they are really good but you just need the cheap ones from the supermarket. Also to keep an open tube of sikaflex usable for next time seal the open end with plastic and/or tape then keep it in the fridge, it should last for ages without setting in the tube.

Rather than a bead of goo in a tube, I've often used rubber hose, set in a routed groove as a replaceable gasket. Assuming a home made hatch, locker lid or similar, I've used a router with a straight cut bit and plowed a shallow groove, around the perimeter of the contact area. A rubber vacumn line, fuel line, etc. can be glued or fastened into the groove, so it stands a bit "proud". When the locker or hatch lid comes down to close, it mashes the tubing, which is captured inside the groove and a very good seal results.

An alternative thought to ponder . . .

Make sure to check what materials is used for your ports to ensure you don't get any reaction between the sealant and the plastic. Polysulphides aren't recommended for use on ABS or a bunch of other plastics.

From my build thread:

I used BoatLIFE Lifeseal which is some silicone/polyurethane mixture that is compatible with the ABS plastic of the hatches. I believe 3m 4000 (not 4200, unfortunately, because I already had a tube of that) is similar. One 80mL tube was just enough for all 4 hatches, and my tube had a fairly big dried up chunk in the bottom.

Here's an article about sealants.

OK. I have just had a look at that article Andy and after having a closer look at what I've ordered I see it's not compatible with ABS plastic which is what my inspection ports are made of. The only silicone/polyurathane sealant I can find is Boatlife Lifeseal but I cant find it anywhere here in Germany. I find it hard to believe that's the only product available.

Kev.

I misunderstood the question and Kev. is correct, you need a hybrid polyurethane/silicone and BoatLife offers one as Life Seal. You should be able to order this on line and have it dropped shipped to your door.

3M does offer some alternatives in the hybrid sealant market. In order of preference 3M-760 Hybrid Adhesive Sealant, 3M-740 Hybrid Sealant and 3M-4000UV Hybrid Adhesive Sealant Fast Cure. 3M -760 is higher tack and has better grip then 3M-740, while 3M-740 makes better gaskets. 3M-4000UV will yellow less and has a fairly aggressive adhesion and also dries firmer then the others.

Thanks Par.

I've just ordered Boatlife from your side of the planet. No one seems to stock it here and the only suppliers of 3M sell in bulk quantities.

Thanks guys for your help.

Kev.

No use to you now, but I've taken to using this stuff.
FixSeal MSP Clear
Use it for bonding all sorts of things, including inspection port rings.
The tech sheet / MSDS doesn't specifically exclude ABS, and older bonds to
ABS items have no visible signs of deterioration. It is similarly priced (in AU)
to Sikaflex marine sealers - about AU$24 per cartridge. (Folks in north
America paying a fraction of that price may now climb back on their chairs...)
cheers
AJ

The sikaflex or polysulphide options are best. I usually just glue the port in place. The screws are not often needed for small boats and are sharp on the back side (of the bulkhead).

It can be worth giving the glued on port surround a bit of a heave. I do know of one or two over the years that have popped off with a bit of pressure. If so you have just made a very satisfactory gasket to use with fastenings.

MIK