Deck thickness???

[JustStartin]

How thick is the deck on a CP-19 at/near the tabernacle for the mast?  I'm working on installing a backing plate due to the tabernacle pulling out of the topdeck and need to know how long the bolts should be.

Thanks!

[Salty19]

I'm not sure exactly, but would guess about 1 1/4" (though the backing wood).  Add clearance for your washers and nut. If you have an XL version, add another 3/8". 
Like anything, best to measure your specific need.

If you have a dremel tool or air powered cutoff wheel, you can always buy long bolts and cut them for an exact fit. 


On this topic, on my old 16 i put 3M5200 adhesive sealant under my tabernacle when resealing things.  Looking back, this may not have been so smart.  It's never coming off now--or at least would be extremely difficult . Use bedding compound here for sealing.

[Craig Weis]

Well if you take your tabernacle off the deck then you can measure with a piece of wire how long the bolt should be.
Go to the search box above and type in tabernacle.

I posted a few years ago how we repaired the tabernacle on Captain Rank's CP-19. It popped out when we were hefting the mast up, so we dashed over to YachtWorks bought 4 [2-1/2" ?? screws and cut them to fit the acron nuts when done], four flat washers, four locking washers, four finishing washers, four acorn nuts and a large tube of 3-M 5200 slow set. Drilled four 1/4" holes clean through the cabin top [one hole went through the cabin light mounting plate, we didn't see that till we snapped off the lens looking for the 'lost' hole. No big deal. Can't see the acorn nut with the frosted lens back on.

We had the stick up and on the water in less then 3 hours. Sailed the next day. The wood hard point under the compression post was all rotty and wet. We just filled the entire area with 3-M 5200. Stiff as a wedding cock and hard as a rock. Those screws are not ever coming out.

I don't know why the factory doesn't bolt the tabernacle clean through. They just use these stupid little screws.

skip.

[Bob23]

Skip:
   Maybe the factory views this as a breakaway issue. In a serious dismasting, better to have the tabernacle break off than loose a whole section of deck. Still, I agree it should be beefier. I imagine that area on my 23 is beefier...no compression post. I seem to remember some kind of rivet holding my tabernacle down- no visable screws.
Bob23

[Craig Weis]

"Still, I agree it should be beefier. I imagine that area on my 23 is beefier..."

Hummmm I'm thinking not beefier in terms of dog house deck thickness but simply through bolts instead of screws would be much better. Short screws at that! Since the screws don't stick out into the inside of the overhead these are no thicker than the tabernacle and deck with a smidgen more for the washer and finishing washers.

Finishing washers are those collar washers that the head of the screw fits in and is what the 'raw' edge of the mast stands on when erected in the tabernacle. The edge of the mast on my boat never touches the flat plate of the tabernacle. Be sure to have those finishing washers under the screws or bolts. I have not changed over to 1/4" ss machine thread screws on Comfort & Joy yet because my screws have not pulled out yet. And be mindful that the tabernacle is not suppose to hold the mast up, but simply there to act as a pivot point and to keep the base of the mast anchored.

Just for poops and grins figure the standard strength of steel. Black iron or stainless, makes no difference it's the same.
So 10,000 lb times the thickness divided by 4 is the safe working load of steel.
Or each 1/4" bolt x 10,000 lb divided by 4 = 625 lb x 4 bolts = 2,500 lb to sheer off the 4 bolts.
That ain't gonna happen! The mast cannot move port/starboard or fore/aft that much at it's base to cause sheer of 4 bolts.
And I think the epoxy impregnated woven fiberglass cloth layered in and hardpointed can take nearly that much force. So I'm not worried about through bolting.

What holds the mast up is the standing rig.

As far as breakaway these Com-Pacs were never meant to go out to sea and be turned turtle with a rouge wave.
There are limits and this kind of seas exceeds these design limits.

I think the arch from port/starboard on the 23 is fine and does the same job as the compression post.

skip.

[crazycarl]

Bob23 is right.
Every sailboat I've owned had the tabernacle or mast step attached with no longer than 1/2" screws.
I went thru a dis-masting last February, the tabernacle tore loose with minimal damage to the cabin top.  The tabernacle was secured with four 1/2" screws and one 4" screw in the center that went into the compression post. 

The bow pulpit was thru bolted. When that was pulled off, it took off the deck underneath it, damaging the boat to the point it was cheaper to purchase another one. 

[brackish]

It is a break away issue or a least cost sacrificial issue.  The dangerous time is when the mast is being raised or lowered.  If you lose it laterally and the tab is set to bend then pull out then no real cost to repair.  If you have a through bolted, back plated tab, it does not break away and you bend the mast extrusion.  Once it yields, that aluminum will not reform without cracking.  Very expensive mast replacement.

When I replaced my tab, all deformed from the PO's mast raising and lowering adventures, I went back with the same short screws.  So far, with my new mast raising system, have not had to test the breakaway theory.

With regard to the deck thickness on the 19, call Hutchins, they will tell you