I've finished laying out the deck of my stitch and glue dory based on Montana River Boats Honky Dory. My question is should I install bulk heads to compartmentalize different sections, or have one big open space. My thinking is that if you hit a rock next to a bulk head you could punch a hole in the side of the boat. Were as if you had only one bulk head up front then the hole side/bottom could have a whole lot more flex.
Hope I am explaining myself clearly.
I have a 16 foot framed boat with front and back compartments (not a full canyon style boat) and am in the planning stages of a fully decked 18 foot framed boat. I do not know a lot about stitch and glue, however have a ton of experience repairing cracks and holes in my framed boat!
It really is a trade off, the flex of a non-ribbed boat is great, my dad has one that was built in 1968 and still runs great, if you have no bulkheads, you and your friends could climb in and have a party! However your gear will slide around if not secured and you could have a serious weight and balance issue that could cause you to hit the rock from the weight shift. I would imagine having one open chamber would be easier to clean and sponge unwanted water out after a trip.
A company called Boulder Boat Works in CO makes a half breed plastic and wood dory that is gorgeous. They use one big compartment. You could talk to Andy there and pick his brain on how his works.
A framed boat with bulkheads obviously has no flex, but if one compartment fills with water from a hole (or an unclosed hatch......why do you laugh ?) you still have 4 or 5 compartments left that are still in tact for flotation. Numerous bulkheads keep your gear in relatively the same spot, but you can't have any parties.
If you hit a rock hard enough, a hole will appear no matter how you build it, I am spending my life learning how to avoid those buggers...
I think theres something to be said for the deck support that bulkheads provide. I like the idea of a dance party on my decks, and without a few bulkheads, that wouldn't work so well...you've got to put in footwells also, seems that footwells and bulkheads go hand in hand. and lastly, I think bulkheads add a lot of stiffness and strength that I will really appreciate when I'm on the bubble line dropping into Lava...
You are right on the mark. I have seen a bottom punch through right next to a bulkhead as you describe. There are ways to deal with this condition. Bulk heads with a 3/8 plywood bottom will lead to trouble. The side is less trouble then the bottom and chine.
Another friends boat took a rock to the chine at Joe Hutch on the Green. Without a bulkhead you will take on a lot more water. So it is my opinion that bulk heads are a good thing. My white water boat is a Honkey Dory as is Jeremy Christensen's boat. A bit small but it works well.
I have a 3 yr old whitewayer stitch and glue Honky Dory. I've put two holes in the bottom of my boat, and one in the chine. First rule is just don't hit rocks. Build your boat our of cardboard and fiberglass you'll probably be ok, just don't hit any rocks.
Ok, so you're definitely going to hit some rocks. Bulkheads do prevent the bottom from flexing, and if you hit a rock hard enough, something is going to give and its not going to be the rock. But if you build the bottom stout enough, the damage should be minimal. Use at least 1/2" fir or other long grained plywood for the bottom, def. don't use Okoume that the HD plans call for. For the bottom, that is. The two holes in the bottom of my boat occurred right at the base of the mid-forward bulkhead, the lowest point of the boat's draft. Both were minor, but enough to expose plywood and start soaking up water. So they required quick repairs on the river just to keep water from soaking in. No real structural damage.
The hole in the chine was massive. I hit some hard schist broadside in the bottom of Westwater at Hades Bar, blew a hole in the chine the size of a grapefruit. Water poured in, filling the compartment beneath my footwell. Luckily this happened while ferrying to our lunch spot, so we just flipped the boat over, mixed up a batch of 5 min epoxy and wood flour and crammed it into the hole, let if kick, covered it with gorilla tape and floated high and dry down through the canyon. Without the bulkheads, a hit like this would quickly make it incredibly difficult to maneuver your boat, bad if you punch a hole in the boat in the middle of say Big Drop 2 and have to run Big Drop 3 as a submarine.
I've decided, with the consenceis of everone I've talked to to go with bulkheads. As for the bottom, I've already finished it with 3/8" i didn't buy okoume, I got the cheaper marine grade form McBeths. I don't know if that is any stronger than okoume (it looks like a hardwood so I doubt it)so I figure I'll punch a few holes in it and hope I don't sink. As for the Big Drops, I've already swam the most of #2, I don't want to try it in a wooden submarine.
You'll probably put a couple holes in it, but you won't sink. My main issue is when I hit a rock and expose the plywood which begins to soak up water, and I feel like I need to make an immediate repair to keep the water from soaking in. This is a pain in the butt, though not difficult, just time consuming. I am in the process of putting a plascore (honeycomb polypropylene) "shoe" on the bottom of my boat to reinforce against rock hits to the bottom of the boat, and reinforcing the chine area with biaxial fiberglass tape.
Based on what I have been reading the fir marine ply is not made to the same standards as the marine grade okume ply is that not true in your experience? I could certainly save some money by buying the fir ply for my Honky Dory build.