Island Packet Chainplate Replacement

[a64pilot]

Originally Posted by Paul L

How was the design changed post 1997?

I believe it was just a change in materials from 304 to 316L.
I think but am not sure that the 316 plates are slightly larger in thickness, but am not sure.
The L is an alloy of 316 that is better for welding, lower carbon maybe? Unsure, just know it is the choice if your welding 316.

[Paul L]

Originally Posted by a64pilot

I believe it was just a change in materials from 304 to 316L.
I think but am not sure that the 316 plates are slightly larger in thickness, but am not sure.
The L is an alloy of 316 that is better for welding, lower carbon maybe? Unsure, just know it is the choice if your welding 316.

If they are still encapsulated and not inspectable, then it would still make me feel uneasy on a boat that is older than 10 or 15 years. There's certainly enough IPs out there that any inherent defects with the newer approach should be pretty well known.

[a64pilot]

Way I see it, is if you have a boat worth more than say a quarter million $, then just plan on spending $10K and know you don't have to worry about it for a long time.
My boat isn't but she is not a newer IP either.

Then you can argue that mine lasted 30 yrs too, and the newer ones have a better chain plate metals wise.

Two years ago I think I got hit in a squall with full sails up with 45kt or so winds and got knocked down, Genoa completely in the water, among other things I was worried it might fill with water, but chain plates held

[Badsanta]

If no encapsulating are they just bolted to the hull. Or are they glasses in or what. Not trying to be a pain I just can't visualize it.
My IP turns 30 this season and it's on my list. Thanks

[Stumble]

Originally Posted by a64pilot

There are all kinds of different skills required in designing and building something as complicated as a boat.
I can only assume there was no metals expert, I know the correct name, just don't ask me or my IPad to spell it.

I have run into all kind of screw-ups in some very experienced aircraft manufacturers, and you just have to ask, what were they thinking, how could they have done this?
Well sometimes what it is, is they messed up one, but got the other
999 things right, but it only takes one to be infamous.

My guess and it's only my guess, is that the risk of chain plate leaks was underestimated.
Likely if they could have always been kept dry, lifespan may have been 50 yrs or more? Mine are 30, have been leaking lord knows how long, and haven't broken that I know of

The real issue isn't that IP designed a bad product from the get go, but even after it was pointed out to them that the design has a major defect they have continued to build with the same design for decades, knowing this was in the future of every new boat they built.

The design originally and today relies on an absolutly perfect goop bond to keep salt water out of the encapsulated plates, if I tried ever fails, even for just a few days then failure is just a matter of time. And of course because they cannot be inspected absent the deconstruction you are doing now, no one I have ever heard of has inspected IP chainplates without replacing them. The added cost for the metal just isn't that much compared to the inspection costs.

Absent corrosion a real lifespan of about 25 years is optimistic. You still have to contend with work hardening which is purely a function of use not damage.

[Frankly]

On a couple of different occasions I had long conversations with Tom Broom at IP about the chain plate issues. I was looking into some NDT (non destructive testing) techniques to use on existing yachts. Nothing ever came of it, but in the 90's The use of 304 SS was industry standard. Nothing went into the design of these yachts without the blessing of Bob Johnson and he had a ME degree from Florida and a MS in Naval Architecture from MIT along with being the company founder and president.

The most common failure location was along the weld where a short section of angle was attached. This angle transferred the shroud load to the area along the gunnel of the yacht and was not encapsulated but did have a layer of putty to make an even bearing surface to the uneven glass layup. Slightly lower on the main chain plate tang was a flat bar welded across all three (cap and fore and aft intermediates). At each of these 3 welded intersection strands of FG were wrapped over the connection and splayed down the hull sides. Bob Johnson referred to this as his "belt and suspenders" system. This lower junction area was covered with a layer of glass and made a perfect catchment for water entering unsealed chain plates. Some of the failures also occurred in this area but this type of failure was often detected by some movement in the main tangs but the top angle half held and so the process did not come to a mast over the side end.

In the late 90 the material was changed to 316L (L being a low carbon better welding) alloy and more corrosion resistant. Also along the way IP discovered that over time 5200/ SS bond would fail and recommended re bedding with a high grade GE silicone (Silpruf). Did mine 11 years back and no evidence of any water intrusion. In the IP Owners Manual BJ makes a point of requiring regular topping off of this silicone seal.

Nothing lasts for ever in a marine environment and we is all a lot smarter than we was 25 years back Ask the US Navy about welding 6061T6 aluminum in a marine environment. I own a 26 YO IP and I worry about chain plates and aluminum water tanks, but I consider it a small issue compared to all the other things I like about my ship. Rotten deck core is a real show stopper IMO. Ain't going to happen in an IP.

[DeepFrz]

A great opportunity to add some closed cell insulation.

[a64pilot]

Originally Posted by Badsanta

If no encapsulating are they just bolted to the hull. Or are they glasses in or what. Not trying to be a pain I just can't visualize it.
My IP turns 30 this season and it's on my list. Thanks

Not the best video to display construction technique, but it's all I know about, there is one place in the video where you see a chainplate going in

https://youtu.be/iB3qzgxvYY8

[Stumble]

Originally Posted by Frankly

.... ....

Nothing lasts for ever in a marine environment and we is all a lot smarter than we was 25 years back Ask the US Navy about welding 6061T6 aluminum in a marine environment. I own a 26 YO IP and I worry about chain plates and aluminum water tanks, but I consider it a small issue compared to all the other things I like about my ship. Rotten deck core is a real show stopper IMO. Ain't going to happen in an IP.

Titanium really does last forever. At temperatures below 600F it has an expected service life of 2,000+ years according to the USN.

A64, it just crossed my mind, you might want to have an engraver etch "6/4 Titanium" across the crown of the chainplates. So down the road the next owner knows what you have done.

[brucebach]

Appreciate all the valuable information. I have a 1992 IP-27 (#346) and noticed that Bob Johnson designed boats such as the Com-Pac 27/3 with external chainplates. Do people believe this is a better method, done for aesthetics (i.e. to look traditional/'salty', like Pacific Seacraft), another reason? Aside from possible resale implications, mentioned above, any reasons for not taking this approach, which I presume would be less expensive and afford easy inspection?

[angelfish2]

Thank you for this thread, 64pilot. We have a 1994 IP 32 and have thought about having this done. Are you at the Hinkley yard in Stuart? Did you consider Snead? I will be interested in the quality of workmanship you received. Thanks again.

Oh... hi Frank! :waving:

[Frankly]

In my opinion most of the load in the original IP design is carried by the cross angle welded and located just under the gunnel. On a pure external bolted chain plate the hull side takes the entire load. Obviously there are many successful designs configured like this. Bolting an external tang on an IP might work if you get the bolts through the internal SS assy (providing the original are somewhat intact) but to get the alignment and nuts would require removing some of the same internal woodwork that replacing the factory setup requires.

[a64pilot]

No, Mack Sails is doing the work, they do not have a yard, but I guess use Britt Point Marina a lot. It's a working yard really although there are several Sportfishermen that dock there, no amenities, not very good place to live at all, no cleats on the old wooden docks either, something that always annoys me, so so guess that is a pet peeve.

I know there is a group that does this in Tx, and I think some that travel, but so don't know anything about them.
One minor thing is the water heater comes out too, so maybe this is the time to replace it as well? I am with a cheap water heater with an aluminum tank, that may bite me someday.
However the original 30 yr old water heater is still working fine, with its aluminum tank, so who knows?

The short time that the factory was out of business, they seemed to recommend Mack Sails.
However the most vocal of them on the IP websites is from my understanding a Retired School Teacher, and maybe a Sales person, so maybe not real knowledgeable about technical aspects.

[a64pilot]

As Frank says, the load path for external plates is different, I believe that majority of the load on the original design is the hull to deck joint takes the majority of the load, with the glassed in portion also of course distributing load through the hull.
You could do that with external plates. It moves the stays out slightly, not enough I wouldn't think to matter, and as I have heard others here comment, looks Agricultural, and as Frank says, what's to gain?

I would hope that if there are to be any new IPs that they consider not a design change, but simply a material change to Titanium. Since the fall of the Soviet Union many years ago, Ti just isn't that expensive in the small amount we are taking here, it's not as if we were talking about the hull being made from Ti.

Trivia, but I think the Soviet navy had a class of submarine that the hull is Titanium? Alpha's maybe?

[Kenomac]

Originally Posted by a64pilot

Two years ago I think I got hit in a squall with full sails up with 45kt or so winds and got knocked down, Genoa completely in the water, among other things I was worried it might fill with water, but chain plates held

Just curious... how come your boat doesn't round up into the wind when you get slammed? Is that due to the full keel? We've been clobbered a few times with fifty knot gusts with full sails up, and our boat rounds up.