I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
ABL1111@AOL.COM
Hulls thru-Bolted or Not ?
Moderator: Jim Walsh
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Tom C
Re: Hulls thru-Bolted or Not ?
</LI>
TomCambria@mindspring.com
If you check in your CD manual you can find a schematic of how CD did the hull to deck connection. To my way of thinking it is far superior to the way inferior boats are put together. On cheaper boats the hull and deck are molded with a horizontal lip running along the edge. This system can be recognized by the rubber strip that is typically put over this seam to hide it. In the cheapest construction these two lips are pop riveted together and covered with a strip of rubber. In a little bit better construction these two lips are bolted together with fiberglass cloth run across the joint on the inside before the rubber strip is put on the outside. CD doesn't use this sytem at all. The hull is layed up with a narrow deep "u" in the hull which is, of course, vertical. The deck is layed up with an edge that turns down and fits into the u on the hull. So that when the hull and deck come together the deck tab is actually pushed down into the u on the hull like putting a piece of toast in a toaster. Rather than two thin edges that you try to bolt together you've got a massive joint a couple of inches thick with no edge that needs bolting together . That's why CD can have a little piece of teak as a toerail which is mainly esthetic and has no rubber strip running around. CD says there has never been a deck joint failure on a CD and I certainly believe it. I also have never heard of one leaking. Since we don't have lips, where would you put througbolts if you wanted to add them? Remember Hal Roth had to take his boat apart in Japan to fix this seam? Poor guy didn't have a Cape Dory. Check this BB and I believe you will find there has never been a posting about a failed or leaking deck/hull joint. At least I can tell you mine never has leaked a drop much less failed.I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
TomCambria@mindspring.com
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Larry DeMers
Re: Hulls thru-Bolted or Not ?
</LI>
I have to admit that this fact surprised me greatly, until I went to my manual, and had a chance to look at the drawing of the hull/deck joint. While I would believe that the bonding material between the two inturned flanges is a superior water-tight seal as long as it is not fractured, it would still make me far more comfortable if they had dropped in a good S.S. bolt every 6 inches during the hull/deck bonding process, which would tend to help the two surfaces maintain their positions relative to each other.
Fortunately, Cape Dory did through-bolt and back up their deck hardware quite well..ie; stanchions. These are spaced a ways apart, true, but the through-bolting/backing up of these components along with the chainplates seems to be sufficient to prevent movement of the flange, allowing the polyester bedding material to do it's job.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30c ~~~Sailing Lake Superior~~~
ldemers@win.bright.net
I have to admit that this fact surprised me greatly, until I went to my manual, and had a chance to look at the drawing of the hull/deck joint. While I would believe that the bonding material between the two inturned flanges is a superior water-tight seal as long as it is not fractured, it would still make me far more comfortable if they had dropped in a good S.S. bolt every 6 inches during the hull/deck bonding process, which would tend to help the two surfaces maintain their positions relative to each other.
Fortunately, Cape Dory did through-bolt and back up their deck hardware quite well..ie; stanchions. These are spaced a ways apart, true, but the through-bolting/backing up of these components along with the chainplates seems to be sufficient to prevent movement of the flange, allowing the polyester bedding material to do it's job.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30c ~~~Sailing Lake Superior~~~
I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
ldemers@win.bright.net
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Russell
Hull-deck joint of the CD 36
</LI>
The CD 36 has the usual inward turning flange, not the U-shaped groove that Tom C describes. It is through-bolted in a variety of ways. (1) Most significantly, there is a steel backing strip, 1/4" thick, 4 inches wide, about four feet long, even with the mast, with tabs glassed into the hull. The four chainplates and two midship stanchions are bolted through the deck, hull, and this backing strip. This is an extremely strong structure. (2) The jib-sheet tracks are on the toe rail, from just aft of midships back to the transom. This track bolts through the hull-deck joint every few inches. (3) All the other stanchions also bolt through the hull-deck joint, to their own backing plates. (4) The remainder of the toe-rail bolts through the hull-deck joint, but not as frequently as the part that carries the jib-sheet track.
The hull-deck through bolting is not regular, eg, every 6 inches. Nonetheless, it is hard to find more than a foot of the joint without a through-bolt. I have found no leaks, though there is evidence of a past leak, suspiciously where a swim ladder used to hook onto the toe-rail at the boarding gate. I've since felt this part of the joint several times, during rain, and it was dry.
Having strong bronze stanchion bases, four-bolted to backing plates, with eyes for attaching blocks, gives several places along the boat where turning blocks or ad-hoc attachments can be made.
I have no worries about the strength of the hull-deck joint. As to leaks, water tightness cannot be guaranteed by mechanical strength, nor do sealants last forever. I believe every structural joint in a boat should be accessible, for inspection, and if necessary, for resealing. I can get to every inch of the our hull-deck joint. If it ever develops a leak, I will be able to find it and seal it.
The CD 36 has the usual inward turning flange, not the U-shaped groove that Tom C describes. It is through-bolted in a variety of ways. (1) Most significantly, there is a steel backing strip, 1/4" thick, 4 inches wide, about four feet long, even with the mast, with tabs glassed into the hull. The four chainplates and two midship stanchions are bolted through the deck, hull, and this backing strip. This is an extremely strong structure. (2) The jib-sheet tracks are on the toe rail, from just aft of midships back to the transom. This track bolts through the hull-deck joint every few inches. (3) All the other stanchions also bolt through the hull-deck joint, to their own backing plates. (4) The remainder of the toe-rail bolts through the hull-deck joint, but not as frequently as the part that carries the jib-sheet track.
The hull-deck through bolting is not regular, eg, every 6 inches. Nonetheless, it is hard to find more than a foot of the joint without a through-bolt. I have found no leaks, though there is evidence of a past leak, suspiciously where a swim ladder used to hook onto the toe-rail at the boarding gate. I've since felt this part of the joint several times, during rain, and it was dry.
Having strong bronze stanchion bases, four-bolted to backing plates, with eyes for attaching blocks, gives several places along the boat where turning blocks or ad-hoc attachments can be made.
I have no worries about the strength of the hull-deck joint. As to leaks, water tightness cannot be guaranteed by mechanical strength, nor do sealants last forever. I believe every structural joint in a boat should be accessible, for inspection, and if necessary, for resealing. I can get to every inch of the our hull-deck joint. If it ever develops a leak, I will be able to find it and seal it.
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Catherine Monaghan
Ours is thru-bolted and bonded
</LI>
The hull/deck joint on our 1986 CD32 is thru-bolted every 6 inches as well as being bonded together with adhesive.
catherine_monaghan@merck.com
CD32 Realization, #3
Rahway, NJ
Raritan Bay
catherine_monaghan@merck.com
The hull/deck joint on our 1986 CD32 is thru-bolted every 6 inches as well as being bonded together with adhesive.
catherine_monaghan@merck.com
CD32 Realization, #3
Rahway, NJ
Raritan Bay
I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
catherine_monaghan@merck.com
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Matt Cawthorne
My 1982 cd36 is bonded and bolted.
</LI>
Alan,
My memory tells me that the bolt spacing is something like every 6 inches, but I never measured them so I can't say that the spacing is 6 inches everywhere. I have never found any evidence anywhere on the boat that there is or ever was a leak at this joint.
matt
mcawthor@bellatlantic.net
Alan,
My memory tells me that the bolt spacing is something like every 6 inches, but I never measured them so I can't say that the spacing is 6 inches everywhere. I have never found any evidence anywhere on the boat that there is or ever was a leak at this joint.
matt
I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
mcawthor@bellatlantic.net
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John R.
Re: Ours is thru-bolted and bonded
Our '83 CD30 is thru bolted and polyester putty bonded as well.The hull/deck joint on our 1986 CD32 is thru-bolted every 6 inches as well as being bonded together with adhesive.
catherine_monaghan@merck.com
CD32 Realization, #3
Rahway, NJ
Raritan Bay
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Ken Coit
Re: Hulls thru-Bolted or Not ?
I claim no intimate knowledge of the hull-deck joints, but here is the text on the CD-36 hull-deck joint from NQ #18, Summer of 1982, Page 80:
As we approached the end of the production line another unusual but simple alternative solution to a major problem in fiberglass yacht construction was found. The usual practice in developing a strong hull/deck joint is to rely upon a heavy mastic for sealing while giving strength by installing stainless-steel bolts at 4"-5" centers on a lip of about 2". Cape Dory's system attempts to keep the mechanical strength of bolts but also to eliminate leaks by reducing, insofar as practical, the number of through-deck fastenings. Thus they extend the lip to some 3 1/4" and use a semi-rigid polyester bonding compound with considerable sheer strength. The joint is held tight by fasteners during the bonding process. After curing, these are replaced by 1/2" stainless bolts at 12" centers. The latter are then covered by a well-bedded teak toerail whose screws pass through both deck and hull flange for additional strength. A teak rubrail is then screwed into the hull molding. It is significant that the thickness of the hull laminate at the flange is some 3/8", substantial in a vessel of this size.
Our thanks to the authors, Fraser and Jean Fraser-Harris.
Ken Coit
S/V Parfait
CD-36 #84
Raleigh, NC
ken-shelley.coit@worldnet.att.net
As we approached the end of the production line another unusual but simple alternative solution to a major problem in fiberglass yacht construction was found. The usual practice in developing a strong hull/deck joint is to rely upon a heavy mastic for sealing while giving strength by installing stainless-steel bolts at 4"-5" centers on a lip of about 2". Cape Dory's system attempts to keep the mechanical strength of bolts but also to eliminate leaks by reducing, insofar as practical, the number of through-deck fastenings. Thus they extend the lip to some 3 1/4" and use a semi-rigid polyester bonding compound with considerable sheer strength. The joint is held tight by fasteners during the bonding process. After curing, these are replaced by 1/2" stainless bolts at 12" centers. The latter are then covered by a well-bedded teak toerail whose screws pass through both deck and hull flange for additional strength. A teak rubrail is then screwed into the hull molding. It is significant that the thickness of the hull laminate at the flange is some 3/8", substantial in a vessel of this size.
Our thanks to the authors, Fraser and Jean Fraser-Harris.
Ken Coit
S/V Parfait
CD-36 #84
Raleigh, NC
I just fininshing reading Practical Sailor's Guide / synopsis of the CD30 ( thx Jerry ), and read that the hull and deck are not thru bolted ... Is this true ? And if this practice changed, for the better, when did CD start to thru-bolt their hulls ?
Thx,
Alan
ken-shelley.coit@worldnet.att.net