Custom Extended Swim Platform

[tpenfield]

I got the coring material installed and the 'J' Bolts installed.

I am running short on resin, so things will have to wait until I get more supplies.

 

[fallguy]

Glass looks dry.

Maybe you are cutting the dry stuff away?

 

[tpenfield]

Glass looks dry.

Maybe you are cutting the dry stuff away?

Yes, the core strips and glass weave is only wet-out underneath (for now). The top and rest of the glass weave will be wet-out with the next layer of glass/resin.

Having all of the strips and glass weave pieces pre-cut and organized worked out well. I put the core down in no time.

 

[tpenfield]

Progress update . . .

I have the core pieces glassed in on both decks of the platform.

The 'navtruss' worked out OK . . . a bit thirsty on the resin, but fine. I had to go pick up a few more gallons of resin. The VE stuff has gotten expensive over the past year . . . sort of wished I had started with poly resin.

I have the remaining embedded hardware installed.

Next steps will be a bit more glassing and trying to figure out 'boxing' in the rear edge area of the platform to make it like an outer skin.

 

[fallguy]

Quite a project.

Decoring that would be a pita unless you could use a router. If that is what you mean.

Another option would be to laminate a piece of 1708 on..... You could laminate it on a plastic bag and cut it out and glue it on with thixo. Then trim it.

Not sure if I fully understand, but trying to help if possible.

 

[tpenfield]

Here are some 'bevel' pieces installed at the step-down area to provide some stiffening (hopefully)

Here they are all glassed in with 24 oz WR.

I still got to figure out finishing the rear area, but in the meantime, I'll work on some pylon stiffeners.

 

[fallguy]

I would have just filleted and taped that.

A gusset would have been better still.

 

[tpenfield]

I would have just filleted and taped that.

A gusset would have been better still.

Perhaps they are gussets

 

[tpenfield]

Here is a wire frame diagram of what I am thinking for the 'boxed in' area in the aft-most section of the platform (purple lines). This approach will require threaded inserts into a starboard material backing (white lines) for the ladder mounting hardware, which could be problematic if the threads ever fail. If I left the ladder mounting areas open, then I could use a typical thru-bolt, but the boxing structure would be more complicated.

The purpose of this structure would be 2-fold . . .

1. Support the ladder abutments
2. Provide some streamlining for the underside of the platform.

I'm thinking I could build the box structure from the 1/2" rigid urethane foam sheets that I have left over from the core material, and then fill the cavity with pour-in foam. (USCG approved 2# density is what I have on hand). Afterwards, I could round corners and do some shaping, then cover it with glass. Might be good to vacuum bag it for curing.

Thoughts?

 

[tpenfield]

Another option would be to go with thru-bolts for the ladders, in which case the boxing structure would need to look something like this . . .

It would be a bit more tedious, but the ladder mounting would be more reliable.

 

[fallguy]

Too tired now. Try for tomorrow, sorry.

 

[tpenfield]

I think I prefer the thru-bolt approach vs. the threaded inserts for mounting the swim ladders. I will probably set up a resin infusion to apply the fiberglass encasing to the aft structure that I have drawn in post #145. I think I can set up seal tape around the perimeter of it once the foam is all done and shaped. Then set up a couple of feed lines, a vacuum line, and the bagging.

 

[fallguy]

You can thru bolt, but you might want to sleeve the core if I am understanding.

The minimum, of course, would be overboring and filling and redrilling thixo.

I hate to mention it, but I am not a fan of using light foam here. I would probably use a minimum of 12# or even use plywood (I doubt you would). I just don't trust 5 pound foam for any odd forces.

Of course, I am just understanding the concept that these will be holding ladders. I am not fully understanding the forces and where a light foam might fail from a 250# person climbing up and putting some odd torque on it.

 

[tpenfield]

Thank you. Your input is making me think through the design in more detail; much appreciated.

The foam is just to fill the void and make the shape. The strength will be in the fiberglass (hopefully) . . . not really relying on the foam for anything but the shape. A triangle - being the strongest shape - is what is designed around the areas of the swim ladder support, where the stress will be the highest. Basically, a triangular shape on each side of the bolt locations - amounting to 8 triangular shapes. So, I'll just want to make sure I use enough fiberglass in those areas.

I could also contour a rib in the flat areas between the bolt locations for added stiffness for when the 'fat guy' climbs the ladder.

 

[tpenfield]

I filled in the surfaces on my wire frame drawing for a more realistic representation of what it should look like. . . .
.