ABI Porthole size

I need to replace the gaskets in the 6 opening ports. I understand that you have to order the gasket as a precut part for the size of the port. Anyone know out there what the porthole size is or how it is measured ? I think it is either a 6’ or 7". Would also be good to know if there is an alternate source for gasket as they want about $ 12 or $14 per port.
Thank you in advance
Mark Giegel


The ABI portholes are 7" and the ABI gasket part number is 131221. I don’t know of any alternative sources.

Thanks John. Seems expensive for a gasket but if it keeps the wate out…I guess it’s a small price to pay.
Best to you


I replaced the gasket in IDUNA’s 10 portlights in 2001 for less than $20 in materials by making my own gaskets from Buna-N square O-ring cord stock. I purchased 1/4" square cord stock from Paramount Packing and Rubber, Inc. (PPR) in Baltimore -410-789-2233 . PPR will ship the material to you.

You can also purchase this material from www.mcmaster.com . Type “Buna-N square O-ring cord stock” in the search box to find the material. The current price for 1/4" square stock is about $0,85 per foot.

You will need an industrial super-glue to stick the ends together. PPR and McMaster stock this item

PPR is a small shop and the price will be cheaper.

Measure the thickness of your current gaskets. They are probably 1/4" X 1/4" in cross-section.

To make the gasket:

  1. Remove the old gasket and clean out the gasket seat in the portlight.

  2. Using the cord stock, measure the amount you will need plus 1" to 2" more.

  3. Cut one end of the measured piece square with a single edge razor.

  4. Starting at the top of the portlight, press the square end into the seat and work the material around the portlight.

  5. When the free end meets the starting end of the stock, trim the free end square, such that when seated it forms a continuous ring.

  6. Pull one end out of the seat about 2 inches, apply super-glue and fit the material into the gasket seat, such that the two ends make good contact to form a continuous ring gasket.

I used a wire brush bit in a dremel tool to cleanup the gaskets seats before fitting a new gasket.

Let’s assume it will take 20 ft to fit of cord stock to make 10 new gaskets, then 20 ft X $1/ft = $20. I used (pi X D) X (number of portlights) divided by 12"/ft to estimate how much material I need to purchase.

I also replaced one gasket for the glass port by cutting my own from Buna-N sheet stock.

You should be able to find a gasket shop in your area where you can either purchase cord stock or have them cut gaskets from sheet material. Making your own gaskets from cord stock is the least expensive approach.



Thanks for the information on sourcing. I do have access to McMaster Carr and will check it out. Did you find that the Buna material was the right hardness to guarantee a good seal and still have a memory in material ? Thanks again
Mark Giegel
SV “Lightfoot”


I used neoprene instead of Buna-N. The shop stripped the cord stock from sheet material. They will not do that again. Dimensions were 5/16" X 1/4". It worked just fine. I have a tendency to over engineer my projects. Buna-N is fine and I suspect the stock gaskets offered by ABI are Buna-N - a very common rubber compound.

Durometer on most O-rings, gaskets and cord stock is 70. We have never had any leaks around the portlight gaskets. After I replaced all the gaskets, I adjusted the hinge set screws such that there was a small gap between the portlight and its flange when the portlight is closed without dogging the portlights down. You do not want to over compress the gasket at the top. I have a friend who asked me about gaskets for his Flicka.

Mike ordered his cord stock and super-glue from PPR and followed my instructions to make gaskets for the portlights in his boat. The process is easy to do and cheaper than purchasing gaskets from XY$. Your cost per gasket will be on the order of $2 for a 6" portlight based on $1 per foot of square O-ring cord stock.

McMaster is a good source of materials. I use them all the time but you pay for the inventory they stock. Try PPR, I suspect their prices will be cheaper. When you telephone, a person will answer the phone and quote a price. The people at PPR are really nice.



Thanks Rod, appreciate all the help here
Best to you

Instead of butt joining them together use a scarf instead.It will take more time to get the cut right but you will get a longer glue surface.
Jolie Brise

I ended up getting the gaskets for portholes from ABI. They fit fine. The 1/4 x 1/4 O ring material from Mcmaster Carr did not work as the cross section required was rectangular, not square. The square groove in the port was smaller than the 1/4 gasket. I could have forced it in the groove but was afraid it would pop out.

A note of caution to anyone who plans to remove the ports: Mark the port and location for each porthole. If possible keep the parts for each port assembly together- do not assume you can interchange the parts. ABI is notorious for using the casting house du jour and many times the parts are not identical. I noted that some of the bolt spacing on the finishing rings and port housings were not the same from one port top another.

Mark Giegel


Sorry you had trouble using the square O-ring stock. Did you measure the width of the portlight grove with a caliper? When I did my ports, the 0-ring stock proved to be a snug fit for the grove in the portlight, as were the original caskets. After 5 years, the gaskets have not popped out and I expect will remain in service for many years in the future.

For future reference, after I installed each gasket, I dogged the port down and left it dogged down for a week to let the rubber seat and conform to the grove.

Burn-N and neoprene will “adhere” to most metal surfaces when placed under a low compression load, as is the case when one closes a port and dogs it down. They will also develop compression set and conform to the grove in the portlight.

This is all water under the brige now. Please, next time I suggest something, feel free to e-mail further questions or post them in the BCC forum.


Thanks Rod
No matter the job, it’s always a learning experience
Best to you

For other BCC / FC owners who will be replacing their port o-rings, I found a great substitute, made by Perko, I think.

There are many items that are on the shelf at Port Supply wherehouse, the wholesale distributer for West Marine, that are not listed in either of their catalogs.

Perko makes this “T” section neoprene-foam just for opening portlites, the “T” leg is 1/4" X 1/4" which seats in the ABI groove and glued in with 3M weatherstrip contact adhesive.

The “T” cross piece is less than 1/8" thick crowned and about 1/2" wide.

It comes in a 10’ length, you cut to size, with a scarf joint, glue, and put the joint on the upper part of the port.

Mike Anderson told me about it, and turned L & L on to it too.

It works great and I have had no problem with it for almost 10 years, now, and still no leaks

The West Marine part number, if not changed, is : 268344 I just checked the WM website and this number is still good and they have the 10’ lengths in stock for $ 14.99 ea (3/6/07).

Perko also lists it in their 2007 web accessable catalog page # 129 , Fig. 0461, as Portlight Weatherstripping, (www.perko.com)

  • Note: The catalog illustrated weatherstrip section looks like it has a “wedge” shaped “T” section top, where as what I purchased had a more traditional crowned “T” shape.

I have found another use for this weatherstrip. I routed a 1/4" groove around the sides and bottom of Calliste’s scuttle hatch drop board and glued in the weatherstripping there too.

Hi Doug. Did you use this weather stripping for round or rectangular portlights??

Hi Dan, I first used the Perko portlight weather stripping on my BCC, ABI round
ports .

I did purchase a set of “O” rings from ABI , but didn’t like the hard rubber feel, like what Rod says is a durometer value, I think comparing the ABI and Perko , the Perko is much more spongy, so that might be less durometer, or degree of “shore” or some such, I am not that knowledgable .

I don’t know why the Perko catalog section illustration of the weatherstripping , differs, from the actual cross section of the stuff I purchased from West Marine, but the Perko cat illustration is different.

One of the more important things that I did to my portholes, was to remove the entire bronze port and coat all the cabin plywood edge surfaces under the porthole with epoxy, because I saw a little dry rot starting at the bottom of the fwd stb porthole.
I think that water was from condensation under the portlight bronze mounting ring, filling a gap between the bronze spiggot, and the cabin side cut-out ,that the 3M 5200 didn’t fill.

Ask Ron Walton, of FC Majita how to remove the ABI Bronze spiggot, his idea worked just fine .