stays chain plates?

hello guys, I am restoring a 54ft sailboat brand SeaMaster. The company went out of business while producing this vessel and never finished it. I got it for a steal but now I need to figure things out because there aren't many drawing, but I have all the parts.
I'm interested in understanding the chain plates for the shrouds in relation to the forestay and back stays. What i mean is that I have these huge stainless steel chain plates for the shrouds (2 on each side) and these little plates that I believe are supped to be for the forestay and one for the backstay.

I am just puzzled about the difference of sturdiness of the two sets, meaning shrouds chain plates vs stays plates. Is it normal?
here are some more details:

1. Port and starboard plates are 40inch long, 2.5 inch wide and half inch think with 11 holes for the bolts.

2. Then what I believe the forestay plate, is a 4 inch by 6 inch squared deck mounted plate with a ring welded on it and a backing flat plate iof the same size without the welded ring, all sandwiched together through the deck with 4 bolts.

3. The back stays (2 of them) are similar to the main chain plates I described above but just half the length (20 inch) with 5 holes for the bolts.

I'll see if I can add some pics, but I was just curios in general if anybody can clarify things and/or maybe provide some links that explains why the forestay and backstays are so small compared to the main chain plates.

Sorry I'm not super technical so if I lack of proper terminology I don't mind the sailor attitude as I learn faster when I get yelled at LOL.

 

Re your first photo, with the massive pair of plates, how long are the bolts / studs connecting them?
Are the two plates intended to be each side of a main bulkhead, with the top ends sticking through the deck?

Re your second photo, I doubt that the forestay would be bolted to something like this, when the port and starboard chainplates are so much more massive.
You mention 4 bolts, but there appears to be 6 bolt holes in the photo?

Do you also have a mast for the Seamaster?
If so, does it have a single or double spreader rig?
I am wondering if it might be single spreaders, and your two chainplates on each side are for the cap and single lower shrouds?

Re your Seamaster 54, does she look similar in any way to the Seamaster 51 in the link below?
2006 Seamaster 51' Sailboat sailboat for sale in Florida https://www.sailboatlistings.com/view/87981

Can you perhaps post some more photos of the deck areas on your Seamaster where these chainplates are supposedly located please?

 

I agree with the points raised.The two large plates could quite well be on either side of a main bulkhead with one for the cap shroud and one for the lower shroud.The other fitting is a bit small for a forestay and I'd be a bit concerned about the whole rig being reliant on that one welded tang for it's integrity.There are lots of other locations where it would be fine.

A long while ago there was a post here about the boats 54' SeaMaster Sail Construction photos https://www.boatdesign.net/threads/54-seamaster-sail-construction-photos.7759/ .Sadly it doesn't tell us much and the image links are only likely to work if you have a username and password.If the designer is still in business they might be able to provide information but it will need to be worth their while.

 

Thank you both for your quick response.
the bolts are 7inch long making the spacing between the two chain plates to about 5 inches when bolted. I think I will have to add layers of plywood to the bulkheads to make them think enough where the plates will go.
Yes I believe they are supposed to sandwich the bulkhead so that one plate acts as the back plate for the other and vice versa but there isn't any drawing about that so is really just a guess.
You are correct is 6 bolts for the other smaller chainplate my bad.
Yes I have the mast and it has two sets of spreader attachments (Double spreaders) , I don't have the spreaders though.
I have attached a pic and marked where the mast and chain plates are supposed to go based on bulkhead location.

I say that boat on the link you posted actually and is very similar, same company but it does not have any chain plates on it either.
I added more deck photos but I can take specific ones if needed.

Wet Feet, i tried to open those links and could not, not sure what the issue is.

Do you think I could put the forestay/genoa on the bow roller (picture).
I also added the only drawing I have.

Guys thank you so much for any help.

 

To me your story doesn't add up. The chainplates in your pictures were clearly mounted before, they are not new. If they came from your boat you should not have any questions about where they need to go and how, there would be holes in the deck and bulkheads/knees that line up with them and imprints in the paint.
Since you say the boat boat comes from a yard sale, the most likely scenario is that they don't belong to your boat, they were just around and got thrown in to seweeten the deal. Same thing with the mast, if you don't have a clear drawing identifying the dimensions you don't know if it belongs to your boat.
Chainplates and masts aren't worth the gas to bring them to the scrapyard unless there is a crate full of them.

I advise you to hire a local NA to go trough your existing drawings, then come out to the boat, asses the build, and calculate and draw you what's missing.
I know that's not what you want to hear, but this is my opinion.

 

I agree that professional advice should be sought,the boat is too far from complete to allow guesswork.I would be extremely surprised if the bulkhead had local doublers to bring the thickness up to 5"-half that would be more typical.
I wouldn't attach the forestay to that bow roller fitting without being quite certain that the load was being distributed into the structure adequately.Which may mean additional glass and large backing plates.There may be other places in the boat where reinforcement is needed but hadn't been added by the time construction was halted.Which is why a professional would be a very useful ally.

 

hello WetFeet and Rumars, you are absolutely right, the chain plates and Mast (and more) came from another vessel. This forum is my first attempt to find help in understanding what I need to do: do I need to get different chain plates and if so what type/size. Is there a specific way to mount them, or specific wood/fiberglass etc. I'm doing the interior right now and that is the relatively easy part, just labor intense but in the meantime I wouldn't mind to do some research and learn.

Do you have any recommendation where I can find that type of expertise? would a rigger know?

Thank you for your help
Daniel

 

Daniel, Rumars has already offered you a suggestion as to what you should do - he said :

And Wet Feet has endorsed this.

Edit - what other drawings do you have for the boat? Can you post some photos here of anything / everything that you have please?

 

While there certainly are rigging shops that can do rig design from scratch, they are not common. And those that do usually have a NA doing the heavy lifting, either as a permanent employee or consultant.
I advise that you get this sorted out before you complete the interior, you don't want to tear into the cabinetry to mount the chainplates.

All your drawings have a name in the bottom right corner, that's where you should start. On the one you posted I can just read "drawn xxxx & masters(?) april '89". I would start with those names, the original designer could still be in business or recently retired and available for consulting work. NA's tend to keep copies of their drawings, so if you find them (google, facebook, etc.), you could be in luck.
Otherwise find a local to design you a new rig from scratch. While this job can be done via email, it's tedious without complete drawings, a local can visit your boat and see for himself what he needs instead of endlessly directing you to measure and photograph this or that.
You find a local NA by asking around in person (boatyards) and online research.

 

thank you bajansailor I was asking advise on where I could find the professional advice that Rumars suggested and Wet Feet endorsed.
The drawing I have attached is the only one I found but I will look around again and see what I can find. Also I have plenty of pics and can take more if anything specific is needed.
I assume I would at a minimum need to buy a Chain plate for the forestay, I just need to find someone that can suggest where I can find an expert that can maybe come see it in person or ask for measurements and pictures or something like that.

 

oh shoot, thank you Rumars, I didn't even notice that on the drawing. Excuse my ignorance in this matter but.... what is a NA?

regards
Daniel

 

Stop on the interior.
A small vessel's furniture is often structural. Or more accurately structural elements are often disguised as parts of interior furnishings.

Not all of the necessary interior structural elements may have been installed before the manufacturer quit.

A N-avel A-rchitect will advise if more interior structure is needed.

 

These folk are all fairly close (I presume) to you in Miami - you could try calling them to see if they might be interested in a project like yours?
Best 4 Naval Architects in Miami, FL with Reviews - YP.com https://www.yellowpages.com/miami-fl/naval-architects

 

thank you, i have not built and was not planning on building any furniture against the bulkheads so I should be fine.
Thank you for the NA explanation I'll start researching on that.

 

bajansailor thank you!!!!!!