Moving Chainplates to hull exterior on Alberg30...

[WingRyder]

Hello all, I am new to sailing and I am particularly interested in a few specific sailboats right now, in the 28'-32' range (i.e. Allied, Pearson, Alberg...). I have a question... From my research, I see that Allied had a habit of glassing over chainplates, and most people modify them, and the Alberg 30, has inadequate chainplates that should be upgraded and reinforced with heavier bolts (let's leave alone the mast issue for a later post ).

My question is this, how much would it effect the geometry of the standing rig, to move these chainplates to the hulls exterior? It seems that it would only be moving them 2-3 inches outward. It seems like it would be a big advantage to eliminate 6 potential leak points into the cabin. I would certainly reinforce the hull to meet the demands of chainplate stresses, but more than likely, they would be mounted directly outboard of the already existing chainplate supports.

Any thoughts would be greatly appreciated. My focus right now is on the Alberg 30. I friggin' love this boat. But I have other full-keel/modified fins, that I'm interested in. But if anyone has experience with Alberg designed boats in the ~30ish foot range. I would appreciate your feedback.

Thanks.

-Harrison

[rbk]

Depending on your track locations is will affect sheeting angle and ability to point to some degree. Not knowing the boat too well, but a quick image search, you may have to hack the cap rail up some which may or may not allow water to infiltrate the deck/hull joint but looks minimal if any.

[WingRyder]

Originally Posted by rbk

Depending on your track locations is will affect sheeting angle and ability to point to some degree. Not knowing the boat too well, but a quick image search, you may have to hack the cap rail up some which may or may not allow water to infiltrate the deck/hull joint but looks minimal if any.

I am mostly concerned with the 6 port/starboard,... beam supports. Sorry, I'm a novice and don't quite know the correct terms... but my goal is to have the standing rig as visible as possible, that is accessible and maintainable, and eliminate as many deck holes as possible. I am still not very familiar with the bow and stern rigging of the A30, but I would really like to move as much as possible to the exterior. I am concerned with strength as well as potential leakage. Perhaps I am too paranoid, as I have limited sailing experience, and I've never sailed in open ocean before, but it seems that many blue water boats have external chainplates, and I can see the advantages of that. If it will significantly effect the rigging geometry, especially in ways I can't foresee, I would not attempt it. I feel that I am a competent enough builder to construct the project properly, but I am certainly not an engineer. The change in physics, seems to me to be nominal, but what the hell do I know? lol.

[rbk]

Many have done it on many different boats. If there are butresses (beam supports??) they may play a role in the superstructure, maybe not. If there are just knees (thicker portions where the chainplates are attached against the hull) then you’ll only have to live with less portability to windward (maybe 5 degrees, maybe not even noticeable) and ensuring a good deal on the cap rail.

[WingRyder]

Originally Posted by rbk

Many have done it on many different boats. If there are butresses (beam supports??) they may play a role in the superstructure, maybe not. If there are just knees (thicker portions where the chainplates are attached against the hull) then you’ll only have to live with less portability to windward (maybe 5 degrees, maybe not even noticeable) and ensuring a good deal on the cap rail.

Having done a TINY bit of research, much of it on Atomvoyages.com, it seems that the A30 has only support knees for attached chain plates. But! The knees, apparently provide enough support to the hull, to this very successful design. If I were to simply move the chainplates to the exterior of those knees, I can't see a significant added stress on the hull... perhaps, extending the knees down the bulkhead an additional 18" or so, to distribute the load, but these points are already supporting the mast load.

EDIT: I just looked up the Tayana 37... WOW, what a beautiful boat! Old school, Perry design! That is exactly what I'm seeking... only a tad but smaller.

Again, I am certainly NOT an engineer, and I would certainly want to reinforce everything. I can't see that moving the rig outward by a couple of inches would effect the headsail significantly... but again, I am not YET a sailor. I have seen many people sailing the A30, and it seems that the A30 dips the leeward deck into the water A LOT! ... when close or beam reaching! The Alberg designs have seem to have a shallow freeboard at the beam, and I would like to be able to completely shut out the water.

This may be too much work for an insignificant problem, but I would like to seal the deck as much as possible, to avoid potential seawater intrusion.

Thanks RBK, for your help. I appreciate any, and ALL advice you can provide.

[MartinR]

Originally Posted by WingRyder

Again, I am certainly NOT an engineer, and I would certainly want to reinforce everything.

This is maybe not the best approach. Most items on boats are over-engineered anyway. Find a design you like, sail her for a while and then think about changes when you have learned a bit more. There are normally good reasons boats are designed the way they are.

[WingRyder]

Originally Posted by MartinR

This is maybe not the best approach. Most items on boats are over-engineered anyway. Find a design you like, sail her for a while and then think about changes when you have learned a bit more. There are normally good reasons boats are designed the way they are.

Thanks Martin, very sound advice! My current plan is to find a boat, in the next 6 months that is in good condition, spend some time sailing locally, and refit her as necessary. I retire in 10 years, and I would like to make her a sound blue water vessel by then. I am just curious if this is something that is feasible, or even desirable. Your response is certainly grounded in logic and reason. The A30 has made countless ocean crossings and numerous circs! So, who am I to change the design? It is just a thought. I would certainly want to reinforce the knees and lengthen the chainplates, and reinforce the cabintop mast supports (when re-rigging becomes necessary), but I am just curious if external chainplates is something worth pursuing... I haven't seen it done before, and perhaps there is a good reason for that. At this point, considering that I don't even have a boat yet, this is a preliminary question... and one that I would file away as a potential future project and further research.

[Copacabana]

I doubt that moving the chainplates outboard would affect windward performance very much on an old full keel boat like the A30. I also doubt you'd need to reinforce the hull for outboard chainplates. I would suggest making a matching SS backing plate and throughbolting everything. With butyl tape behind the new chainplates you'll have a worry-free, dry and robust system.

On my boat the previous owner moved the chainplates to the outside of the hull and I'm glad he did. No leaks, everything is visible and easy to inspect and even replace (with the mast up). It's certainly a strong and robust setup, with 5 large SS bolts holding each chainplate.

Another option to reduce leaks is build a fiberglass riser (a pad of solid fiberglass epoxied to the deck) to keep the chainplate supports a little higher than the deck so they don't sit in water. If you google Don Casey you'll find an article he wrote on this modification he made on his Allied 30.

[Suijin]

Originally Posted by WingRyder

This may be too much work for an insignificant problem, but I would like to seal the deck as much as possible, to avoid potential seawater...

In my opinion you’re designing a labor intensive solution to a non-existent problem.

If you’re concerned about strength replace the existing chain plates with beefier ones, seal the deck *properly* and maintain it *properly*. Leaks come from bad craftsmanship/materials and poor maintenance.

I know quite a few A30 owners, most of the knowledgeable and competent. None of them have considered your plan.

Be careful about amassing too much theoretical knowledge without tempering it with actual experience.

Is your plan feasible? Certainly. Is it “an improvement? Maybe. Is it a huge amount of work? Yes. Is it necessary? Absolutely not.

[MartinR]

Beefier chainplates are not an improvement on a well-designed yacht. Chain plates are so much stronger than the rigging wire, there is really no need. Rigging wire has a safety factor of about 3, chainplates from 10 upward. They are designed for indefinite fatigue life.

[ottewj]

I have a Reliance 44 that I purchased in 2003. The chain plates were mounted interior and out of sight behind the paneling. I discovered that the plates were mounted to steel that had almost rusted away. I had new plates mounted to the outside of the hull. Also the hull was reinforced to support the plates.
The only draw back is the jibs sheets sometimes catch on the most forward plates.

[SVTatia]

Originally Posted by MartinR

This is maybe not the best approach. Most items on boats are over-engineered anyway. Find a design you like, sail her for a while and then think about changes when you have learned a bit more. There are normally good reasons boats are designed the way they are.

Best advice so far.

You are overthinking the situation and a bit premature, but I understand your concern.

• Yves Gelinas modified his chain plates before his circumnavigation on the A30 and he ended up dismasting and if I remember correctly, some of the bolts gave up. Did you watch his video? Also, you could contact him for his advice.
• One of the structural problems with the A30 is not the chain plates but the mast support, the underdeck definitely needs to be beefed up.
• Before moving the chain plates outboard you need to check the deck-hull joint to determine if it will be impacted and/or need reinforcing - the stresses will be different on the joint itself.

And you are right, the A30s are lovely boats - they look like a mini version of my Luders 33.

Originally Posted by MartinR

Beefier chainplates are not an improvement on a well-designed yacht. Chain plates are so much stronger than the rigging wire, there is really no need. Rigging wire has a safety factor of about 3, chainplates from 10 upward. They are designed for indefinite fatigue life.

The risks are not with the chain plates themselves, but how they are attached to the hull.

[Copacabana]

Originally Posted by SVTatia

Best advice so far.

You are overthinking the situation and a bit premature, but I understand your concern.

• Yves Gelinas modified his chain plates before his circumnavigation on the A30 and he ended up dismasting and if I remember correctly, some of the bolts gave up. Did you watch his video? Also, you could contact him for his advice.
• One of the structural problems with the A30 is not the chain plates but the mast support, the underdeck definitely needs to be beefed up.
• Before moving the chain plates outboard you need to check the deck-hull joint to determine if it will be impacted and/or need reinforcing - the stresses will be different on the joint itself.

And you are right, the A30s are lovely boats - they look like a mini version of my Luders 33.



The risks are not with the chain plates themselves, but how they are attached to the hull.

It was Yves' modification to his mast that resulted in the dismasting, not the chainplates.

While chainplates are engineered to be 10x stronger than necessary, when they sit behind cabinetry or hidden under the deck you can't be sure they are still in good shape. Many people have unpleasant surprises when they pull them for inspection. Mounted outboard they're in plain sight.

[Mike OReilly]

My Rafiki-37 (similar, but nicer than a Tayana-37 ) had its internal chainplates moved to the exterior at some point in the past (a previous owner). I don’t know if it’s changed our upwind angles much, but I really doubt it. And having them exterior, and beefier, makes me feel pretty comfortable when heading offshore.

[SVTatia]

Originally Posted by Copacabana

It was Yves' modification to his mast that resulted in the dismasting, not the chainplates.

na na

“Looking why the mast broke, I noticed that the two lower-shroud chainplates had pulled from the deck, bolts neatly sheared. The mast broke at the first spreaders. I realized it was entirely my fault. I had increased the size of the bolts holding the backstay and capshroud chainplates, but had judged these strong enough. The original lower shrouds were 3/16 in. (5 mm) while the rest of the rigging was ¼ in (6.4 mm) and I replaced the whole rigging with 7 mm cable. I had figured that the resistance to shear of the 3 ¼ in. bolts on each chainplate was equal to the tensile strength of 7 mm cable. Now, I know it was not. …”

Here: http://www.alberg.ca/articles/dismasting-gelinas.pdf


While chainplates are engineered to be 10x stronger than necessary, when they sit behind cabinetry or hidden under the deck you can't be sure they are still in good shape. Many people have unpleasant surprises when they pull them for inspection. Mounted outboard they're in plain sight.

100% agree to your last point.