Which would be less ugly?

[Djarraluda]

3 comments not made above:

1. Whatever you use, you are creating 3 separate sections on the roof, how is this to drain? Give some consideration as to where the water will flow (complete with the associated dirt trails we all hate.

2. Another possibility for securing is to overdrill the top hole to a size where you get a box spanner on the nut (slimmer than a socket) then you could always get a nylon cap to suit that hole and the finish is just a series of neat domes.

3. I would consider the mid section bending moment of the beams, the box section will be a lot stiffer than the angle alternative. If you want to save weight, can you drop to a smaller box section for the stiffness then for the davits, cut the bottom of the 3 inch box so it fits neatly over the smaller section and can be bolted through the sides?

Roger

[Chotu]

Originally Posted by Djarraluda

3 comments not made above:

1. Whatever you use, you are creating 3 separate sections on the roof, how is this to drain? Give some consideration as to where the water will flow (complete with the associated dirt trails we all hate.

2. Another possibility for securing is to overdrill the top hole to a size where you get a box spanner on the nut (slimmer than a socket) then you could always get a nylon cap to suit that hole and the finish is just a series of neat domes.

3. I would consider the mid section bending moment of the beams, the box section will be a lot stiffer than the angle alternative. If you want to save weight, can you drop to a smaller box section for the stiffness then for the davits, cut the bottom of the 3 inch box so it fits neatly over the smaller section and can be bolted through the sides?

Roger

Ah yes... the dreaded water pathways. Never an easy thing to reason out.

As it is, all the water from the roof goes to 2 places. 1. Over the side windows and, 2. Off the aft of the roof which is carried all the way back to the aft beam.

The stiffeners should take a considerable amount of water away from the windows and send it aft. This is a good feature. Could even be used for some rainwater collection. The roof is cambered, so there is a potential for some puddling to occur.

Not sure what else I can do here. I need to stiffen this roof up.

I was thinking about the holes drilled from the top too. That was my initial plan.



Yes, I could certainly drop to a smaller box section forward and tie them in. I was going to do the same with the angle too. Same 3 x 3 angle and tie into the box beam neatly. The length of the section they all sell is 20’ so I have no choice but to marry some different pieces together unfortunately.

[Djarraluda]

Originally Posted by Chotu

Ah yes... the dreaded water pathways. Never an easy thing to reason out.

As it is, all the water from the roof goes to 2 places. 1. Over the side windows and, 2. Off the aft of the roof which is carried all the way back to the aft beam.

The stiffeners should take a considerable amount of water away from the windows and send it aft. This is a good feature. Could even be used for some rainwater collection. The roof is cambered, so there is a potential for some puddling to occur.

Not sure what else I can do here. I need to stiffen this roof up.

I was thinking about the holes drilled from the top too. That was my initial plan.



Yes, I could certainly drop to a smaller box section forward and tie them in. I was going to do the same with the angle too. Same 3 x 3 angle and tie into the box beam neatly. The length of the section they all sell is 20’ so I have no choice but to marry some different pieces together unfortunately.

For the joins, I would both sleeve and scarf to get a secure joint if you want to hide it.
For the lateral drainage, probably not important when at sea, as there will be enough movement to keep it flowing aft anyway. If you want any drainage to low points for when you are moored, I would use a block to enable use of a hole saw and scallop the underside, then glue in some tube to seal the sections. Once the glue dries, grind the base flat before bedding the whole thing down on the roof. Of course you then get the rainwater and dirt back over the windows!
Roger

[KP44]

Just a comment.

Never let the dingy "bounce around". Always lash it securely so it can not chafe, and especially in rough weather.

Beauty is truly in the mind of the beholder. Something that looks functional usually is beautiful. Something that looks unusable or impractical is far less beautiful.

[Chotu]

Originally Posted by KP44

Just a comment.

Never let the dingy "bounce around". Always lash it securely so it can not chafe, and especially in rough weather.

Beauty is truly in the mind of the beholder. Something that looks functional usually is beautiful. Something that looks unusable or impractical is far less beautiful.

Cool second paragraph. Sometimes you can get so caught up in trying to design beauty that you get off track a little bit.

When I was talking about bouncing around, I mean the forces on the end of the cantilevered beams. That dinghy will be accelerating down, up, side to side, all depends on the sea state. So it’s important to account for all of those forces. And even though it should never happen, I also accounted for a dinghy full of water. And the outboard on it. And all the fuel. No reason not to over design that a little bit.

What I ended up going with, since the length I need is about 24 feet, and the longest section is 20 feet, I went for the square tube for the davit part, and then the angle as it moves forward and the dinghy stresses are no longer on the beam.

The right material for the right job in the right place. I think the angle could come in handy for some other stuff up there on the roof as well. Mounting things, just like rslifkin had said earlier.