Armstrong vs. Tempress vs. T-H Marine Deck Plates

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FOUNDER of Classic Parker Forum
Feb 16, 2006
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Newbury, MA
From the post earlier today, about water in the bilge, here's a comparison of these 3 deck plates or inspection ports, as they're also called. People have also been asking "What is truly waterproof?"

-Stock with the Parker boat
-Low profile
-Tempress sells replacement O-Rings for a couple bucks each
-Dirt collects in the O-Ring area and then the groove, making them susceptable to leaking
-Need a tool to remove
-Ugly gray color

T-H Marine:
-New style design, about $12 each
-The full "lid" design covers the entire O-Ring seal, keeping it absolutely clean!
-Low profile, as compared to the Armstong plate
-The design appears to be waterproof
-Spin-off design
-Available in a beige to match the Parker gelcoat (color NOT shown below)
-Height is 1/16" talled than the Tempress plate
-The bolt circle to attach these is a 1/16" to 1/8" smaller than the Tempress plate, so you'll need to patch the old holes and drill new ones

Truly waterproof, HUGE 5/16" thick compression gasket, of considerable durometer
-Projection height above the deck is 1/4" above the Tempress plate and with the "lip" design, (gasket is well back from the edge about 1/4") these are VERY EASY to trip over IMHO if/when mounted "flush" to the cockpit deck

To me, the T-H Marine plate/port offers the best features and hence the best value.


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I’m thinking of going with the TH Marine hatches now. Thanks for the write up Dale.

So the mounting holes on the TH Marine hatches are smaller? Do you think it would be possible to enlarge the holes so they’d line up with the Tempress holes? Maybe with a drill or dremel? Even if a larger sized screw would be required, I’d rather that then patch and fill holes. What do you think? Dom
Its a shame that those Armstrong plates are so tall.
Dale, do you think the Armstrongs could be recessed flush by cutting a relief for them with a router?

With all the plates in my deck (plus 3 more that aren't in this photo), those tall plates are just too much of a tripping hazard for me.


I do plan on replacing that bilge hatch with an Armstrong this coming season though. :wink:
Even with new gaskets, that Tempress hatch passes too much water through it for my taste.
Megabyte":8uaxh5kd said:
Do you think the Armstrongs could be recessed flush by cutting a relief for them with a router?
Sure, but ... water and dirt will still collect around the rim. You'd also need to do one heck of a smoooooooth epoxy job on the surface where the O-Ring (more of a thick gasket) contacts the floor surface, or it'll leak surer than s#$t.

MByte, if you mean the large rectangular Armstrong hatch, the things I don't like about them is that (1) they too are way tall off the deck, and (2) you need to completely remove the darn thing to check you bilge. It's convenient to just pull up on the handles and check the bilge fast.

I don't get much, if any, in through my rear deck hatch, the Tempress 13" x27" one. But here's what I do. My boat has 3 of them, as the other 2 are up under the foam in the V-Berths. I moved one of the ones not exposed to the sun back to the rear and install a new gasket from Tempress. In a few years, I'll move back the other one that's never seen the sun. Then after that, I'll just rotate them every 2-3 years so they all wear evenly ... sun kills plastics overtime.

Now ... and here's where I feel most people goof up :shock: . Put on your sealant of choice (I now use Life-Caulk for this application) and sit the closed hatch in place with a brick or weight on it. Let is setup for a day and then add the screws (with more LCaulk) and tighten into place. The bedded goop now acts more like a gasket as you'll compress it a bit when tightening down the hatch. It also only needs to be snug ... tightening too much or too much to one side can make the closing be off, it must cock/twist something out of line.

Oh yeah, I also wetout the holes for the fastening scews with thinned Raka epoxy beforehand, as well as making sure the edges of the hatch cutout are properly sealed. I want ZERO water penetration into my deck.
I was just down at my boat and I noticed the caulking was comming out, so I opened the Stock deck plate and there was water , not much on the fuel tank, so i bought two screw down plates and will install tommrow, I like the venting set up , that looks cool !
DaleH":jqls5afq said:
My boat has 3 of them, as the other 2 are up under the foam in the V-Berths. I moved one of the ones not exposed to the sun back to the rear and install a new gasket from Tempress.

Before I ordered the new gaskets from Tempress I was going to steal one from one of my forward V-berth hatches. I never thought about moving the whole damn hatch back aft. :D

Hmmmm. good idea, thanks Dale! Those forward hatches haven't ever seen the light of day, and if I'm paying attention at the helm, they probably won't ever have to get too wet either!

I like the one-hander quick-slam tempress. I'm in there fairly often, I always do a quick inspection prior to heading out on each trip, and that's where my oil is.

How easy is it to remove/install a new gasket on the Tempress slam hatch? Where can they be ordered?

-- Tom
TomS":1q3xp8a8 said:
How easy is it to remove/install a new gasket on the Tempress slam hatch? Where can they be ordered?
Piece o' cake! I can give you a gasket to the 13x23" hatch on SAT if you show up at that boating flea market in Newbury.

Tempress O-Rings for inspection ports/deck plates are available here.

Tempress gaskets for hatches are available here.

Ordering @ Tempress Products 877-234-7466
These pictures are from a similiar discussion we had on I just purchased a set of slightly used Armstrongs from a fellow CSCer and they look great. They will go into the deck where a hole does not exist yet. Eventually they will be installed like this.


Judging from that photo, those hatches aren't as much of a tripping hazard as I thought.
Hmmmmmmmmmmmmm................. :shock:
Update to T-H Marine deck plates:

Weak point of the T-H Marine deck plates: The O-Rings on the plates I installed 'just last season' look like crap this Spring :evil: !

The good news: The replacement O-Ring you can buy from Tempress for $2 fit perfectly and appear to last many seasons :) !
TimC2520":3mkunlcd said:
Those Tempress Slam Hatches that Parker uses in front of the engine, can you buy just the gasket for those?
Yes Tim, click right here.

I have a 2000 MVSC, my rear bilge hatch is

a 13X23 Slam Hatch from Tempress......

On the Tempress site ( it is......

1323 Slam Hatch - Ivory

Not sure when they stopped using the single-lever slam and moved to a different manufacturer.

The hatches on this year's models I saw at
the boat show were a dual cam-lock type.

Mine is the dual cam also. I would like to replace it with an Armstrong hatch but I don't think they make one large enough. I need to go down and measure it.

TimC2520":26cg1lyk said:
Do the old one's come out fairly easily or are they glued heavily into place? Anyone else try to replace these?


I just did this last weekend. Gaskets are just compression-fit in place, no
glue. Old ones come out in a snap and the new ones pop right in..

...a no-brainer.

If you order the gasket from their website, allow about a week and a half for them to get the gasket to you.

Also, the gaskets are so cheap that the shipping is likely to cost more than your total order, so you might want to buy a few for future use or get some deckplate o-rings too, or pool your order with a couple of others to make it more economical.