How to create a arch in joists?
- Thread starter bkvanbek
- Start date
mike93lx
ALLIANCE MEMBER
Wtf? Foot traffic on an arch that is the second level of a raft?
Viper98912
Well-known member
you forgot the point that it also needs to shed water.
I'm picturing this in my minds, but before I comment I really want to see what the OP has come up with
Viper98912
Well-known member
OH COME ON! You know we always love your posts.
jack stand
Well-known member
Don't worry about the rain water, it's not going to pond up on a floating raft unless it's contained.
Skiff Builder
Well-known member
How long is the overhead to be?
Option A:
This is how I spanned 8'6" , arched deck and pilot house overhead on my last boat build. You could scale up the sizes for 12':
Sawed 1.5 x 1.5" curved beams out of 2x10 White Fir stock. 4" high crown over 8'6".
Glued/fastened 3/16" plywood on bottom of beams.
Cut sheets of 1.5" XPS foam to fit between beams. Glued to bottom plywood.
Covered top of beam with 3/8" ACX fir plywood, glued and fastened to beams and foam.
1 layer of 10 oz fiberglass cloth laminated with epoxy resin on top surface, than painted.
Strong, light, insulated, moderately complicated, but somewhat elegant.
Option B:
For a more of a get it done and get on the water :
Saw roof beams out of 2x10 ( lightest specie you can get -spruce/fir)
16"oc
Give it a crown of 4.5" or so.
1/2-5/8 ply on top, glued and screwed with PL Premium. Non skid paint.
Thin 3/16 ply on bottom of beams would really add strength.
Option C:
Standard deck construction. Just pitch entire overhead in direction of your choice.
You can use fiberglass window screen and laminate on top with Titebond 3 wood glue, sprinkle with beach sand for non skid-waterproof deck.
Bunch of ways to get this done.
Option A:
This is how I spanned 8'6" , arched deck and pilot house overhead on my last boat build. You could scale up the sizes for 12':
Sawed 1.5 x 1.5" curved beams out of 2x10 White Fir stock. 4" high crown over 8'6".
Glued/fastened 3/16" plywood on bottom of beams.
Cut sheets of 1.5" XPS foam to fit between beams. Glued to bottom plywood.
Covered top of beam with 3/8" ACX fir plywood, glued and fastened to beams and foam.
1 layer of 10 oz fiberglass cloth laminated with epoxy resin on top surface, than painted.
Strong, light, insulated, moderately complicated, but somewhat elegant.
Option B:
For a more of a get it done and get on the water :
Saw roof beams out of 2x10 ( lightest specie you can get -spruce/fir)
16"oc
Give it a crown of 4.5" or so.
1/2-5/8 ply on top, glued and screwed with PL Premium. Non skid paint.
Thin 3/16 ply on bottom of beams would really add strength.
Option C:
Standard deck construction. Just pitch entire overhead in direction of your choice.
You can use fiberglass window screen and laminate on top with Titebond 3 wood glue, sprinkle with beach sand for non skid-waterproof deck.
Bunch of ways to get this done.
Last edited:
75gmck25
Well-known member
Also be very aware of what that extra weight up high will do to the seaworthy ability of your raft. There was a boat that capsized a few years ago (in the Wisconsin Dells, I think) and they found it had been modified without going through the proper Coast Guard approval for a charter boat.
The original cover for the boat passengers was canvas on a metal frame, so quite light. When the boat was modified they used a wooden cover and supports, but they never considered how top-heavy it was. Once it got into really choppy water it rocked back and forth enough to simply tip over and dump out all the passengers.
The original cover for the boat passengers was canvas on a metal frame, so quite light. When the boat was modified they used a wooden cover and supports, but they never considered how top-heavy it was. Once it got into really choppy water it rocked back and forth enough to simply tip over and dump out all the passengers.