Big Bow Sprit Water Tightness - Methods

[Scott Carter]

I'm waffling on a critical deck plan/rigging issue on my under-construction schooner. Apparently, I need to attach the bow sprit to the boat or something. I'm considering both deck mounted and below deck mounted (through the stem head).
My preference is the flush deck with the sprit passing over the stem head but beneath the deck frames into the foc'sle where it's terminated and buttressed. Enough of a description? THis will give the clean foredeck look that I love on a boat like this. My worry is, of course, water entry up in that sometimes violent area of the boat whith spray everywhere. I have a couple of ideas of how to pass the sprit through the stem head (approx 8", triangular in section) and then into the boat, beneath the 2"x4" cambered deck beams. What I don't have is a way to maintain watertightness. I've considered that the joinery should (stress should) be adequate to provide this, and to an extent I agree with this. But I also see this part of the boat crashing against weak and helpless race competitors....err, I mean 4 foot seas. So, are there any tips or tricks anyone can offer to help with this critical area?
thanks,
scott
p.s. the sprit is a T-section, 8" on the top walking face with a 10" vertical section, 20' long.
Thanks in advance,
Scott

[jehardiman]

How steeved is the sprit? Is there a fo'casle deck? Are you going to heel it in the sampson post? Arrangements all depends on these things.

[Gilbert]

Hi Scott,
I would avoid having the structural integrity of the bowstem compromised by having the bowsprit cut it off below the deck. The integrity of your stem is very important in case of a collision, as you alluded to. Find a way to put it above the deck, or if you do not want it cluttering up your foredeck, engineer some way of supporting it entirely outside the stem. In the old days the bowsprit was the largest spar on the boat and they rested it on the stemhead and it ran through the deck and ended it at the base of the mast. This of course meant the tip of the sprit was quite high, which I doubt you would want to do.

[artemis]

Another option which has not been mentioned but which goes far back in time is to "offset" the sprit to either port or starbard of the stem piece. This preserves the integrity of the stem, yet allows the sprit to pass within the hull, below the deck and be well secured. Can't think of specific examples, but I've seen it drawn/referenced many times in books.

[PAR]

You could also use knees on each side of the stem, sandwiching the sprit, trailboards which have some structure, cat's whiskers keeping it aligned on the centerline and a bob to resist rig tension, maybe with a striker if necessary. Your sprit should be strong enough to hole a vessel twice your size and total a craft your size or less. This should give you an idea of how strong it needs to be.

Typically they live on deck or just above it and land on a keel stepped bit, while resting on top or over the stemhead. This "triangulation" (keel, stem, bit and sprit) is usually enough "purchase" to get the job done. Large vessels have gone to greater pains for the strength. A cantilevered beam requires an incredibly strong purchase.