metal screws when installing inspection port ??

Thread starter #1
I am wondering if drilling the holes and using metal nuts and bolts is really necessary. It is a real pain.
I am using 3m Marine Adhesive 5200 and the reviews about it say how strong it is by itself.
Thanks to everyone in this great forum. I am a newbie who's got the sunfish bug


New Member
Yes, use stainless screws and nuts. I install mine inspection ports with silicon, that way if I need to remove them I can.
If you're using 3M 5200, you won't be able to remove the port, so screws might not matter much, and a self-drilling sheet metal style screw is probably fine. If you want to be able to remove it in the future, use 3M 4200, and go with nuts/bolts.
I have done many of these deck port installs and just use clear silicon goop under the lip of the port and 1/8th inch diameter aluminum pop rivets to secure the port to the slight curve of the deck. It is cheap, easy and effective. Be sure to plug the pop rivet holes with left over silicon to prevent leaks.

Alan Glos
Cazenovia, NY

signal charlie

Well-Known Member
Staff member
Try it. Take pictures. 3M 5200 can be released with heat, lots of it. Think fire! No seriously, it can be softened up with a heat gun down the road if needed, but be careful to not soften the gelcoat and fiberglass around it.

As far as curving the port, some ports don't like that and bind. We use smaller ports on the stern for that reason. The port can also be bedded in a base of chosen goop, and use a plastic scraper to shape a nice base around the edge of the ring.


Well-Known Member
The deck is not flat. You need the screws to curve the port ring to the deck.
Why not bed the port in 3M 5200 / 3M 4200—trim neatly while setting—then use aluminum pop-rivets?

A screw-in port will mate properly with its integral O-ring, and the use of pop-rivets eliminates the sharp points underneath—waiting to be discovered—when using screws (especially). :confused:

Sealed all-aluminum pop-rivets (25 @ $9.95) are available from Wal-Mart.

My advice? Don't let them pop, but "snug them up", then carefully grind off the central mandrel. The pop-rivets are intended to repair aluminum, and will eventually split "factory" holes in plastic. Stainless pop-rivets would be even "more worser". :eek:

signal charlie

Well-Known Member
Staff member
Might be hard to see but we left the port and starboard edges of the inspection port proud, and flat. It is bedded in marine grade sealant, carefully applied so as not to have sticky sealant on the deck other than under the ring. We snugged down the hardware just to where the marine grade stainless nylock nuts and washers didn't rattle around.


We add our votes to not leave sharp screws poking out under the deck, especially on boats we are selling to other folks.

Check out those stripes! They're cut from adhesive backed sailcloth.
Just a short p.s. The Hobie Cat folks used to sell a nice 6" dia. inspection port with a slight curve in the lip to match the curve of a deck - perfect fit for a Sunfish deck (fore or aft) and allowed the screw-in port to screw in and out without binding.

Alan Glos
Cazenovia, NY