I need a replacement deck cap. I bought one but the thread is wrong. Mike Quill doesn’t have any but thinks they were Sea Dog. Do Sea Dog one and a half-inch caps have the right thread? What is the correct thread?
Hi Nick,
Around May 2021, I asked a similar question on the old Google forum. And got a few responses, you could search for that on Discourse, but none helped me. My deck caps are 1-5/8 “ diameter, and I never did find a proper replacement. My local marine store has several different brands and sizes, including Sea Dog, but I couldn’t find one that fit. There are no markings on the boat on them to tell the brand name, at least I didn’t see any. I did find a black PVC plumbing plug 1-5/8” dia at Home Depot. Not a perfect fit, but will work if needed temporarily if you were away cruising and lost original cap.
Don
I saw this but, as you say, there weren’t good responses. The replacement that I purchased has the right cap size but the wrong thread. Mike Quill suggested Sea Do which list the thread size and type but I don’t know if it is the right one.
If you know someone with a 3D printer, they could probably make up a temporary replacement cap in PETg with some measurements of the diameter and thread pitch. Unfortunately, for a proper stainless steel part I would guess it will be necessary to replace the entire fitting.
I would look for a marine consignment store for used ones. They usually have dozens of them to find the right fit.
Hi Bob,
Yes. The most useful thing someone could tell me is what the thread is. Mike Quill thinks the originals were Sea Dog and Sea Dog names the the thread (this is all new to me) but I don’t know what the thread is on my boat. Does anyone know the thread for the caps and throats that Hinterholler made?
Nick,
You may find this video helpful…
https://youtube.com/watch?v=Gdvtw0pTAOs&si=lgkAERhpVdKBj5n8
You can buy a thread pitch gauge on Amazon for about $10. If you already have digital caliper, then you should be able to figure out the size and thread for your deck cap. Digital caliper are about $30 at Canadian Tire, but often on sale for $15-$20.
Thanks. That is very helpful. I think that the deck cap I bought had a thread column which is slightly too large. Sea Dog gives the thread size on its deck cap. I should be able to get the thread measured at the club’s marine services, if not I can buy the equipment. To my surprise, Google AI was helpful on explaining the standard N30 fittings. I now know that not all deck caps are alike. It’s a shame that Mike Quill doesn’t have any. The club chandlery told me that on average two a week are lost. It sells a plastic fits all replacement which is what I have now until I work out how to get one the right size.
A Nonsuch was recently burned in a fire. I wonder if she will be parted out for replacement parts for other boats. I wish I was close enough to her to try to save some parts.
Elsie,
You are so far away from Norwalk Ct. Borders are in between you and the boat but you are right in your sentiment. Insurance companies don’t want to be bothered with the value of what remains and it is a big expense to buy salvage boats in that you have to have a place to deal with it, there may be some entrepreneurs that are hip to classic stuff like masts and hardware that may have survived the fire.
Brian
What caused that? Lithium batteries make me paranoid for a disaster like this.
Well, if anyone has access to those parts, I am a buyer of the deck caps. I also think White Water Marine makes the right size. I’m checking.
Nick
416.722.8565
My understanding is that the LiFePO4 (Lithium Iron Phosphate) batteries specified for boats don’t have the fire risks of regular lithium batteries used in consumer electronics, because LiFePO4 batteries will not experience thermal runaway like other lithium batteries, but charging things like laptops and power tools aboard can be risky.
I don’t know the cause of the fire. The picture was from the local newspaper. Rob Cohen visited the remains at the boatyard it was taken to and posted a picture of it from the stern. It was quite a mess.
Search for the topic, Nonsuch On fire – Norwalk, Connecticut
I think they are 1.5 straight threads. Most what you see at hardware and renovation stores are NPT or tapered
If you look carefully on Amazon you can find them, just use the ask a question feature to refine the description
Thank you. I think they are a straight thread - NPT or NPTM - National Pipe Thread Measurement. Found this on Google AI. White Water Marine makes and sells them. I am going to measure the thread first with calipers. If I get a successful match I will let DSiscourse know. I haven’t found anything suitable on Amazon.
FYI, NPT is tapered thread. NPS is straight thread. I have just checked mine with calipers and my newly purchased thread gauge, its NPS 1-5/8" OS diameter and 16 TPI SAE thread. Yours maybe different.
Thanks again. I’m flying blind. Where did you buy it?
416.722.8565