CD 36 chainplates

[Adam Lambert]

Greetings all,
I am considering doing some serious bluewater miles and am searching for the right CD 36, I think that I only want a CD 36, no other designs but just have to find the "right" one.
I am about to fly out ( I live in Australia) and look at an early model ( in the 20's in the production line I think) CD 36 and I have read that the early models have issues with the chainplates.

This does not scare me to much, at this stage, however I would like to find out how much work it is to beef these up / remove and replace them.

Can anyone assist with this please?

Or anyone know of a good CD 36 down under that is for sale?

All the best.
Adam

[Sea Hunt Video]

Adam:

For starters, go to:

http://www.farreachvoyages.com/

John Stone's website is one of the most detailed and exhaustive on Cape Dory 36 restorations, improvements, upgrades, etc.


John is also a frequent contributor to this website. He is an encyclopedia of information on Cape Dory 36 sailboats.

[Matt Cawthorne]

Adam,
The term 'chainplate' is a little misleading when it comes to CDs. They don't have chainplates in the traditional sense of a strap of metal bolted to the sides or piercing the deck and attaching to a bulkhead. CDs have a padeye that bolts through the deck to a metal 'C' channel that runs along the hull/deck joint. It is a dry system if sealed properly from the start. The system is insensitive to bending loads, and that is a big plus for safety. The system seems robust, provided that the bolts don't experience crevice corrosion. I have started pulling one or two padeyes each year, checking the bolts and re-sealing. No crevice corrosion has been identified on my through bolts yet. Some CDs have had issues with corrosion of the backing plate. I would check that. My boat does not have any corrosion on the backing plates that I have been able to detect.

If you are going to do much offshore sailing I would remove fiberglass around the top of the joint between the rudder and the rudder shaft. After removing the glass and foam I would do a thorough check for crevice corrosion. I did this on my boat this year and discovered a significant amount after 33 years in brackish and salt water homes. Crevice corrosion is nasty in that it hides pretty well. I uncovered one 'pit' about 3/16 or 1/4 inch deep and about 3/8 by 1/2 inch wide/long and ground it out, thinking that I had reached bottom. A dye check resulted in an indication in the bottom of the pit. More grinding found another chamber of corrosion. It turns out that to be certain of having removed the corrosion, you have to get a clean reading and then remove antother 0.1 inches (depending on the inspection method it may be more or less) beyond the depth of the clean reading. You can then passivate the stainless or weld back the material, grind to shape, passivate and rebuild the fiberglass.
I scrapped my rudder this year and am building a new one. This is not a cape dory problem alone. Many or even most boats have stainless steel for the rudder shaft

Regards
Matt

[Adam Lambert]

Adam,
The term 'chainplate' is a little misleading when it comes to CDs. They don't have chainplates in the traditional sense of a strap of metal bolted to the sides or piercing the deck and attaching to a bulkhead. CDs have a padeye that bolts through the deck to a metal 'C' channel that runs along the hull/deck joint. It is a dry system if sealed properly from the start. The system is insensitive to bending loads, and that is a big plus for safety. The system seems robust, provided that the bolts don't experience crevice corrosion. I have started pulling one or two padeyes each year, checking the bolts and re-sealing. No crevice corrosion has been identified on my through bolts yet. Some CDs have had issues with corrosion of the backing plate. I would check that. My boat does not have any corrosion on the backing plates that I have been able to detect.

If you are going to do much offshore sailing I would remove fiberglass around the top of the joint between the rudder and the rudder shaft. After removing the glass and foam I would do a thorough check for crevice corrosion. I did this on my boat this year and discovered a significant amount after 33 years in brackish and salt water homes. Crevice corrosion is nasty in that it hides pretty well. I uncovered one 'pit' about 3/16 or 1/4 inch deep and about 3/8 by 1/2 inch wide/long and ground it out, thinking that I had reached bottom. A dye check resulted in an indication in the bottom of the pit. More grinding found another chamber of corrosion. It turns out that to be certain of having removed the corrosion, you have to get a clean reading and then remove antother 0.1 inches (depending on the inspection method it may be more or less) beyond the depth of the clean reading. You can then passivate the stainless or weld back the material, grind to shape, passivate and rebuild the fiberglass.
I scrapped my rudder this year and am building a new one. This is not a cape dory problem alone. Many or even most boats have stainless steel for the rudder shaft

Regards
Matt

Matt,
Bloody awesome response, thank you.
Hoping to get up close and personal with a CD 36 next week and shall take it from there.

Many thanks once again.
Adam

[Paul D.]

This is a schematic of the CD chainplates. I've not seen another like it on any other manufacturer. Seems to work as I've not heard of too many problems with them. Previous comments are correct about corrosion though so they should be easily accessed. I can get at mine through the head locker and hanging locker opposite.

[Jim_B]

Adam -

Per this there was a change in materials around hull # 71 -

http://www.capedory.org/reviews/nqarticle/

" Chainplate construction is again unusual, but has both logical and sound engineering precedent. To remove as much steel as possible, a change has been made here. In earlier hulls a steel web was used, but after hull No. 71, now on the line, it is replaced by an aluminum angle bar. Some three feet in length, this plate is glassed with uni-directional strands into the hull under the lip. It is positioned during the hull layup process, and the first layers of unidirectional are led behind the last layers of roving, thus interlocking the whole structure. Finally, the wide deck plates, well bedded, are bolted through the deck/hull flange and aluminum bar.
This system eliminates any possible movement between chainplate and deck, so often a source of leaks. Since the aluminum plate is molded into the hull, which is also reinforced by the unidirectional glass for a considerable distance down to its thicker cross-section, the loads are evenly distributed and well spread. "

[Jim Walsh]

Adam -

Per this there was a change in materials around hull # 71 -

http://www.capedory.org/reviews/nqarticle/

" Chainplate construction is again unusual, but has both logical and sound engineering precedent. To remove as much steel as possible, a change has been made here. In earlier hulls a steel web was used, but after hull No. 71, now on the line, it is replaced by an aluminum angle bar. Some three feet in length, this plate is glassed with uni-directional strands into the hull under the lip. It is positioned during the hull layup process, and the first layers of unidirectional are led behind the last layers of roving, thus interlocking the whole structure. Finally, the wide deck plates, well bedded, are bolted through the deck/hull flange and aluminum bar.
This system eliminates any possible movement between chainplate and deck, so often a source of leaks. Since the aluminum plate is molded into the hull, which is also reinforced by the unidirectional glass for a considerable distance down to its thicker cross-section, the loads are evenly distributed and well spread. "

I'm always thankful that the CD31 has the chainplates bolted through the hull/deck flange with six additional layers of unidirectional roving and a four foot long 1/4" aluminum backing plate. Zero flex and I've not had any leaks...at least not there

[John Ring]

In 1985 (hull #135) they were using aluminum plate as the backing.

John
CD36 TIARA (#135)