Inspection Ports/Deck Plates


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Thread starter #1
Hello: Is there any generally agreed upon size that is preferable? Small (4") less intrusive, but can you get your hand/arm in near when needed for repairs? Large (6") more finger roomy, but noticeably larger. Or do most folks go with the 5" compromise size? My 1966 boat should be ready to take to the water next Wednesday for the first time under my ownership. I plan on installing 1 or 2 ports at end of summer to get the last moisture out and to have for some in hull work later. Leads to the question where to cut one in order to replace the bow handle backing block, obviously it can't be in the "ideal" location behind the spray skirt, maybe 2? 3? John

Mark P

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I haven't had to mess with that bow handle area yet.

As for the size, I did a 4" and kind of wish that I had done a 6", live and learn.

Enjoy your new boat.
The first fish I ported I used a pair of 4" on either side of the daggerboard. Every one since them I've went with 6 incher in front of the daggerboard; AND if I have any work to do inside the hull I don't mount the port until the work is done to get that extra room that the port inself takes up.
Is there any generally agreed upon size that is preferable?
Not that I am aware of. It depends on the job to be done through the port. I use the smallest possible diameter for the task and as Mike does I leave the ring off for more working room until the repair is finished. Tape those raw edges.

I plan on installing 1 or 2 ports... , maybe 2? 3?
I wouldn't put any more holes in the deck than is absolutely necessary. I fix bow handles through a 4" port on center about 4" back of the handle. I don't mess with a new wood piece I use a drilled stainless plate epoxied to the underside. Bigger hands require bigger ports. I put in a central 5" port between splash guard and daggerboard for general drying. You can always go bigger later. Going smaller has additional challenges.

Like Dan, 4" port for bow handle repairs or installing a hiking strap on a pre '71 SF in the rear cockpit wall, I prefer a 6" between the DB Well and Splashguard and a 5" for the rudder upgrade. From the 6" port, I was able to resecure the bulls eye next to the mast and the cleat for the halyard, install the front strap for the hiking strap as well as reset the foam blocks. From the 5" port, I replaced the backing blocks for the bridle eyestraps (had to cut some foam) and upgraded the rudder system. I used aluminum backer plates instead of stainless or wood. Keep the number of ports to the minimum if you can, do repairs before installing the port ring (tape the hole edges), I use 3M Marine Silicon to seal (can be cut easily if the port needs to be removed for additional repairs) and thru bolt the ring. These three locations cover most of the common repairs on a SF. Good luck
Hi , I also was wondering about inspection ports and was wondering if anyone has a good clean photo of the port on the boat. I used the search and got a rough idea where to place them, but a pic would reassure me. It would be more for stowage than repair like a cell phone, wallet etc. I hate losing them things!:)

Here are some photos for you;

P1 – 6” port between splash guard and dagger board well
P2 – 4” port in rear wall of cockpit for Hiking Strap installation (pre 1971 boats) to install backing plate and nuts on bolts.
P3 – 5” port at stern for rudder upgrade
P4 – 5” port installed to repair hole in hull at transom before rudder upgrade (pre 1972 boats. In this location, you may hit a foam block (forward edge inside of port), no problem; just remove the foam to do the work needed, no need to replace any removed foam. New bracket has been installed since repair.
P5 – Photo showing relationship of wood rudder mount backing block (pre 1972 boats) and relative locations of 5” ports. Yellow string is just a marker between the forward ends of the bridle eyes

Hope this helps.


I was getting online to post the same question.

I was wondering if an 8'' port between the coaming and the dagger board would be to much? West marine sells the 6'' and the 8'' that you can also buy cat bags for so I want to go with one of those two sizes for that location. I've never heard of anyone going over a 6'' port so I think it might be over kill. Any thoughts?
The deck has a curve. It's more on newer boats. 6" just barely fit with the lid keeping a seal. Warping an 8" to the curve might be too much.
Thread starter #11
Thanks all, most excellent thoughts and photos. Two days until my wife and I test how many times we can accidentally jibe without suffering concussions or boom impalement.....:D John
I used three of the clear 6" ports from Jamestown Distributors. They were cheap and high quality. I truly needed all six, (foam block resetting).
I was a bit nervous to make my first inspection port last year on my 1969 'Fish. After all, I was doing a hole in my boat! It was 6 inch port behind the splash guard. Finally, it is not difficult. Important: put a new blade on your jig saw. Cutting will be much faster and easier.

This summer, I installed an inspection port at the back to repair the rudder. It went completely pull off last year under medium air! The backing plate was soaked and rotten, so the screws got loose. So beware!

I have put a 4 inch port at the back but a bit too much forward, so I have trouble to put my arm in the boat because of the lack of depth of the boat. I had trouble to reach under the top plate of the rudder to put to put the nuts. My children had hepl me, they have shorter arms!The place shown on Supercub picture seems OK to avoid that problem.

I have found that a 5" port in the rudder area is all that is needed in either rudder access location. I have upgraded a couple of boats and found that I can get my arm inside with the port ring NOT installed. You can always put a bigger port in where you have a small port.

As Dan mentioned the 8" is too big, a 6" works just fine behind the splash guard. I can reach the mast well, bulls eye (or pulley), most of the foam blocks up front (to Re-set) and the front cockpit wall with out much problem, again with out the port ring installed.

Tip #1 - The lid can be used to draw the cut line for the port. Use a "Sharpie" marker and cut right down the middle of the line and the ring should fit just right.

Tip #2 - Have one port with a clear lid (I have it on the rear port). Any time there is moisture in the hull, it will condense on the underside of the lid where you can see it. Open the ports and let the inside dry out.

The clear lid will show the condensation on the bottom side, but you usually can't see the hull bottom to see if there is any water in the hull, but it only takes a couple seconds to open the lid and look inside.
I'll agree with Cubbie, the clear port still doesn't let enough light through and isn't distorsion free enough to see the hull floor to check for water infiltration.
Besides if you use a Cat bag; which is very useful storage in case of capsize; in the port that would block any view.
The port lid, o-ring, port ring are what keeps things dry. The cat/fat bags are not water proof, just uncoated nylon (similar in weight to the sail), and will let water condence on the bottom of the lid. You need to use a ziplock type baggie if you really want to keep stuff dry. Double them up (2 baggies, one inside the other) for extra security/dryness. If the bag is inplace and you see water condencing, take everything out and dry the bag and other stuff, mold could form on the bag if it remains damp.

Only one lid needs to be clear (mine is the back 5" port), the front can be solid.