Chainplate adaptor separating from deck

[gusmuller]

To all Hunter B&R lovers out there, if you are a hater please just keep your thoughts to yourself. I have owned a 2001 Hunter 380 for about 18 months and last weekend I noticed that the chainplate adaptor on top of the deck was separating from the deck itself.

There are 2 5/15 bolts that secure this piece and absolutely no access down below. I removed one of the bolts and it had about a full inch of thread engagement and some signs of wear on the portion that was in contact with the thru hole in the adaptor plate(picture attached). I place a new bolt with the added 3M 5200 sealant. Has anyone seen this condition before ? Is it an actual problem ? Does anyone have a sketch or print showing how the chainplate is attached to the adaptor ?

 

[gusmuller]

sorry the bolts are 5/16 and not 5/15 !!

 

[dlochner]

Put the rest of the tube of 5200 in the trash. This is possibly the worst product to use on a chain plate. Chain plates will flex and move with changing conditions and tuning. 5200 is an adhesive, not a caulk. It will not allow the deck/hull and the chainplate to move as it needs to move.

The chain plate should be bolted to a bulkhead or knee below. The screws at the deck level should not be a significant part of the structure. The chainplates serve to transfer very high loads to the boat's hull. Those screws should simply help to seal the flange to the hull to prevent leaks.

 

[FastOlson]

There are 2 5/15 bolts that secure this piece and absolutely no access down below.

Even Hunter usually provides access from below... Other owners should have some insight. Hunter, like other builders, used SS deck fittings to "pass thru" the rigging load to an internal grid structure, IIRC.
You sound like you have given it a good look, but best to look again -- there may some cabinetry to remove.
Some time reclining in your ship's 'thinking chair' may help! That and perhaps a drink......

Good luck!

 

[kloudie1]

Carefully check the tie rod that attaches the chain plate to the grid structure. It looks like the tie rod may be kinda loose and the screws are pulling up on the deck.. The gel coat cracks around the chain plate "bump" tell that same story.

 

[Ralph Johnstone]

I can't really say I follow your explanation of what you did ..................... guess you had to be there.

Are you saying the 2001 H-380 does not have the same design as the 1999 H-310 for the shroud attachment shown below ?



You should find this in the cabin directly below the deck mounted attachment on both sides of the boat. Yours may be hidden behind cabinetry. The attachment in the H-310 has a 1/2" stud welded to the bottom of it and the plastic cup covers the 1/2" nut and stud. Under the nut is a heavy washer (approx. 1/4" thick). The cabin top assembly that supports this whole assembly is solid FG and capable of handling the load many times over.

On deck, the two machine screws (seen in your photo) are there to keep the shroud attachment from rotating. I don't know if this is what you removed but they are considerably less than 5/16".



I don't know if you're familiar with the B&R rig, but I suggest you research it thoroughly before attempting repairs to any of the attachments.

 

[gusmuller]

Thank you all for the suggestions and help. What should I use instead of the 5200 for calking ? (got another leak behind the mast where there is a stupid "water collecting basing" and 6 screws holding a bridge and 6 lines, it drips onto my table !)

Back to the matter originally posted.

Last night I spent a lot of time studying the problem, it appears structurally the system is fine with the plate in questions as merely a cap/rotation preventer and a loading point as I originally feared.

The cable/turn-buckle is directly in line with the rod(welded to the plate) and transfers the loads to the hull at a attachment point behind some cabinetry. I suspect a not so precise tolerancing in the manufacturing process that let the fiber and gelcoat at a not so precise angle with the shroud.

The picture below is form the archive of images I got days before buying the boat, that condition has always been there but for some reason I never noticed before !!! Last year during the pandemic I sailed/motored 3000nm !

 

[dlochner]

Thank you all for the suggestions and help. What should I use instead of the 5200 for calking ? (got another leak behind the mast where there is a stupid "water collecting basing" and 6 screws holding a bridge and 6 lines, it drips onto my table !)

There are a lot of choices, perhaps too many. For installing deck fittings, Butyl Tape is often the best choice. In other cases a caulk like 3m 4000UV or 4200 are good options. Some prefer Sikaflex, which has several choices.

5200 is an adhesive with some sealant qualities. Use it only where adhesion is the primary objective. 4000 and 4200 are sealants with some adhesion qualities, use it where flexibility is important and adhesion less important. In general 3m products with lower numbers have more sealant qualities and those with higher numbers have more adhesion qualities.

Avoid silicone products with 2 exceptions, Dow 795 and GE Silpruf. If the silicone sealant smells like vinegar, don't use it on a boat. it gets in to the gelcoat and is not easily removed.

For general purpose, deck fittings, winches etc. I use Bed-It Butyl Tape.

Bedding Deck Hardware With Bed-IT Tape - Marine How To

Originally published December 2003 *Moved & Edited September 2017 Bedding With Bed-It Tape 5/20/2022 IMPORTANT UPDATE BED-IT TAPE IS BACK PURCHASE BED-IT TAPE Countersunk/Beveled Hole Over the years,

marinehowto.com

 

[gusmuller]

There are a lot of choices, perhaps too many. For installing deck fittings, Butyl Tape is often the best choice. In other cases a caulk like 3m 4000UV or 4200 are good options. Some prefer Sikaflex, which has several choices.

5200 is an adhesive with some sealant qualities. Use it only where adhesion is the primary objective. 4000 and 4200 are sealants with some adhesion qualities, use it where flexibility is important and adhesion less important. In general 3m products with lower numbers have more sealant qualities and those with higher numbers have more adhesion qualities.

Avoid silicone products with 2 exceptions, Dow 795 and GE Silpruf. If the silicone sealant smells like vinegar, don't use it on a boat. it gets in to the gelcoat and is not easily removed.

For general purpose, deck fittings, winches etc. I use Bed-It Butyl Tape.

Bedding Deck Hardware With Bed-IT Tape - Marine How To

Originally published December 2003 *Moved & Edited September 2017 Bedding With Bed-It Tape 5/20/2022 IMPORTANT UPDATE BED-IT TAPE IS BACK PURCHASE BED-IT TAPE Countersunk/Beveled Hole Over the years,

marinehowto.com

Much appreciated suggestion. Will report out in a few days !

 

[kloudie1]

Gus, just a thought.. ya might have to remove both screws and the shroud from the chainplate , inject a good sealant (795 or 4200, etc) underneath at the deck, then rotate the chainplate one turn to tighten it against the deck then replace the screws and shroud.. if you carefully mark the turnbuckle threads before loosening, you can put it back where it was. The turnbuckle may have to be loosened 1/8" or so to compensate for the one turn of rotation on the chainplate.. The chainplate should not put any upward force on the deck at all and those cracks in the gelcoat indicate that the plate may be pulling pretty hard.. Consider calling in a rigger to look that system over.. That chainplate is attached similarly to the attachments on the H-34/H-31.. search the posts on this site to get some visuals that will help.. Good Luck.

 

[jmce1587]

I can't speak to the H38 but here is what Kloudie mentioned for a chain plate configuration on the H31. The base plate on deck is attached to the fiberglass for holding with 4 small screws (see H31 construction pic with details on 4 screws). The actual chain plate attachment is welded to a rod that is screwed down into a castle nut that is welded on the underside of the chain plate anchor. I've attached a few pics of my H31 when we had to replace the chain plate anchor. Pics attached are from the H31 owners manual on chain plate set up and actual photos of the deck chain plate base, rod and attachment to foundation plate.

 

[gusmuller]

All,

A half turn was all it needed, replaced the crews with new ones and added a slant to prevent leaks. Today I went out to test it out on 18knots and it was like it came out of the factory 20 years ago !

Thank you all for the kind help and detailed suggestions.

 

[gusmuller]

Well folks,

A sad update. I ended up losing the entire rig a few weeks back. The chain plate in questions pulled out completely and everything else went....

Been trying to dig information on how to rebuild it but not very easy to get it. Unfortunately the way the boat was constructed there is absolutely no way to inspect it unless one disassembles a significant amount of wood work and cut as access hole into the fiberglass. I have done all that and have more questions than answers.

Found a pipe with a square plate, nut and pipe welded assembly that I can only assume it was used to tension the tie rod. My assumption is that once the rod was assembled and tensioned, a vertical steel bar(looks mild steel) was fiberglassed in place to prevent the assembly from rotating itself lose. Lastly the entire area would be encapsulated by fiberglass.

Has anyone encountered this issue ? any suggestion ?

 

[Davidasailor26]

I don’t really know what parts I’m looking at, but IMG_0892 looks like fiberglass that isn’t very well wetted out. Maybe a previous repair or just not very well laminated in the first place?

 

[gusmuller]

That is a steel bar that is lose, I also do not know what the heck it is...in the image 0884 you can see it from below.

 

[jmce1587]

Sorry to hear this news. Pics above in #11 post above when I lost my rig to a similar failure. PM if you want to discuss what I did for repairs on my H31

 

[RoyS]

Why did Hunter want to eliminate the backstay? Was it just to increase mainsail roach? Seems illogical to me.

 

[FastOlson]

Why did Hunter want to eliminate the backstay? Was it just to increase mainsail roach? Seems illogical to me.

It is also to related to moving the main sheet up to an overhead traveler. Gets sailing-related "clutter" out of the cockpit area and increases the potential pool of buyers to include more non/seldom sailors. So far, a successful survival technique in a declining sailboat market for the last 20+ years.
They tried to engineer in (just) enough strength to support the mast with aft-led shrouds (sort of/kind of similar to a J-24) but the loads on the hull structure went up, a lot, and the requirement for very precise layup and production QC went up considerably, and this leads to occasional problems for the boats that are actually sailed very much.
Increasing the roach -a lot - also pleases buyers who look at pictures of all-out racing boats for guidance when shopping, kind of like many builders in the 70's selling pinched-stern "IOR" hulls to newbies who would never ever race under that rule but wanted a boat 'like' the ones they saw in a magazine...
Anyone else remember when Plymouth would sell you a "Super Bird" with a large wing on the back and extended nose, like the ones racing in Grand National circuits? Oh My!
Marketing!! What Fun!!

 

[shemandr]

"Why did Hunter want to eliminate the backstay? Was it just to increase mainsail roach? Seems illogical to me."

Beats me.
I think they wanted to create a new kind of boat coming out of the era (Error) of the IOR masthead rig. I'm speculating that they wanted a rig that was easy to handle for a couple and maybe some kids but would still perform. The 109% jib is easily tacked but is underpowered. The winches could be smaller. They needed the roachy main to make the performance acceptable. In addition they created the arch to make the cockpit more comfortable by eliminating the traveler track in the cockpit and providing a base for the Bimini. The lines (On mine) were designed to be led to the cockpit. In the end, I think it was their response to where they thought the market was going and what they thought their customers wanted. And they had a lot of it right.

 

[RoyS]

Engineers often design structures for calculated loads with some additional safety margin built in just to be sure. These exercises are complicated but engineers enjoy them. However, they often neglect to include shock loads which are largely impossible to calculate. Shock loads can be measured after the design is completed and the structure is built with extensive testing but this seldom is done in the rush to production. Customers experiencing rig failures unfortunately are the testing ground.