Chain plate support

[Tripper]

All other yachts I have looked at, have the chainplates bolted to a bulkhead or hull stiffener. On the Mac,the chainplates are bolted through the hull only. I know 1000's of Macs have been built this way,but it does concern me that there is no adequate strength built into the hull to prevent upward compression forces on the hull. What are chances due to the elimination of bulkheads causing panting under high wind sailing?

[They Theirs]

If you looking for someone to provide a guesstimate of failure, I doubt youll find the answer here. No doubt the factory has tested and maintains some records of structural reliability. There may be some seasoned board members to answer your question. The hull is structurally enhanced at the chain plates and shown to be more than sufficient

[Night Sailor]

I'm no expert but I've noticed that thousands of makers, millions of boats have been made with outboard chainplates fastened to the hull, since the earliest days of wood boats. Both hull attachments and bulkhead attachments work well. The design characteristics of the hull and rigging, are aimed at a particular range of purposes, or uses. Narrow boats versus beamy boats. Work boats versus racers. Ocean going versus party boats. Having the rig inside the rail gives optimum advantage to some desgns, at the rubrail helps others in their intended sail plan or usage. Bulkhead fastened chainplates are often seen on modern racing boats that have very little thickness or strength in their topsides in order ot save weight, so must have a stronger anchor point on a bulkhead inside . Keel stepped boats often have chainplates that are anchored on a floor grid directly in contact with the keel and hull system so forces are directly opposed during a high load rig application. Since the hull curves inward and floor/hull junction is inboard of the rub rail, this necessitates having the chain plates go inboard of the rubrail quite a bit. Even in some fancy cruising boats, the chainplates are exposed for all to see because they are so far inboard that there is no practical way to hide them.

Our Mac rigs are lightly loaded in common use, but engineered well to take a lot more than commonly seen in rig forces, without interior bulkheads reinforcing the sides. The overhead liner in newer models, and thicker hull section on older models seems to do a good job. The fiberlas hull and deck material on the Macs varies from from 1/8" to 3/4" in thickness. It's thicker where it needs to be or has builtin backing plates. All of it is engineered to handle expected and unexpected stress. Macs are tough.

Hope this helps relieve your mind about chainplates on the hull.

[Dimitri-2000X-Tampa]

O'day's have their chainplates attached to a block of wood on the bulkhead. Problem with that is that leaky chainplates over the years causes the wood to rot and they have a record of pulling out. So from that perspective, better to have them anchored in fiberglass.

[Lease]

Pretty sure that it aint where it's bolted, but over how large an area the load is spread that counts.

Almost all manufacturers will put a fairly large piece of ply, or similar in the layup and bolt the chainplate through that. Not sure if that is the case on these boats, but others may know.

I know that when I changed the rig and put running backstays on my tri, I put an eight millimetre thick chainplate, about ten inches long on the back side of a frame in each of the amas. That is a reasonably small area (but the biggest I could find) through which to transmit load, but it stood up to a few pretty good breezes. Don't forget that the tri has to absorb almost all of the load generated in the sails as the boat dissipates nothing through heeling. So unless the manufacturer has bolted directly through the glass (which is doubtful), then you won't have a problem with them, given the sail area and rig style.

[Sea Pony]

I read on the Mac website that they use the chainplates to seperate completed hulls from the molds at the factory. It seems to me, if you can lift over half to total weight of the boat just by the chain plates, they must be at least as strong as bulkhead mounted chain plates.

[Steve K]

There's about 10 layers of fibeglass in the area of the port and starboard chainplates on the X boat, that is about a foot wide and runs from the rubrail to below the waterline.
When I had my Xboat, I lifted it off the trailer using the chainplates.(outboard still on the transom). The factory hauls them around on an overhead track by them during construction. They are plenty strong.

I also careened the boat, using the jib halyard (on dry land). This would put some stress on the chainplates too (and lower shrouds). She held up just fine.

[ALX357]

The plywood bulkheads on my Hunter 22 stayed wet too long from leaks down the chainplates, and rotted thru, unseen, so that if I had not discovered that situation when the boat was on the trailer for a few years, it would have resulted in dismasting in a good breeze. Mac design is much more trustworthy.

[Tom Spohn]

I worried about this when we first bought our boat then learned that the factory lifts the boat out of the mold using the chainplates. I have never heard of one failing.

[Tripper]

Thanks for the input.
My concern is not how strong the fibreglass is where the chainplates are mounted, but the flexing of the hull due to the strut action of the mast pulling the hull in and out when sailing. I have seen boats with stress cracks in the hull due to the hull not being rigid enough. (no bulkheads supporting the hull.)These cracks appear forward of the chain plates. No matter how thick the fibreglass is ,there will always be stress on the hull created by the fixed rigging.

[Catigale]

Roger has thousands of boats out there, and there are always nutcases who will push them far past their intended uses.

I use nutcases affectionately here.

The fact that, to the chagrin of Sailing Anarchy, there just arent reports of Macs failing means all these worries about hull design are an army of straw men.

Just light them on fire - they are easier to clean up that way..

[They Theirs]

These Sailing Nutcases have survived the Flying Monkeys but Hold the Fire!
They are holding their only Bulkhead.

[Catigale]

[Steve K]

Did I mention that my 26x was broadsided by a 65 foot, sleeps 14 houseboat? (yes, several times). No damage whatsoever. The impact was just forwad of the chainplate, down on the side of the hull.

Now, you want to see chainplates pull out? Just go look at an older Catalina 22, particularly if it has been raced a lot. The chainplates on my '77 (six in all to boot) were simply eyebolts that bolted through the cabin top. And YEP....... they will pull through the cabin top eventually, if you keep the rig race tight.

Getting a little tiresome hearing about how cheaply built the MacGregors are, particularly since I've owned other "higher quality" sailboats that didn't make the grade AND I've seen, first hand what some of the Macs have taken and remained in tact.

You want to go out and pay three prices for another name, be my guest, but I have to say, MacGregor is a well built boat, as far as the basic structure goes. Some of the deck hardware could be higher end pieces. But then the new selling price would be a lot more. I tend to re-rig to my own taste, everytime a get a new, or used boat anyway, so this isn't as important to me. But you can't knock the way the MacGregors are layed up and put together. It is industry standard and done well.
I'm no expert, of course, but I do have some background in fiberglass construction, relating to the marine and automotive industry.

1hobie, 2 Catalinas, 2 MacGregors and counting.

[LOUIS B HOLUB]

Steve K -- "dittos" from me on MacGregor strength & quality. The amount of Fiberglass at stress points gives me great comfort. I like the hardware too. The trailer, well, that's another matter...