attaching a transom ladder

[arbarnhart]

I got a flip up transom swim ladder to attach to the back of my boat. I bought it used (I got this budget, see?) and so I don't have instructions. I need to mount 4 brackets against the outside of the hull above normal waterline (obviously I still don't want them to leak). Each bracket has 2 holes, about an inch apart that could take a screw of about 1/4".

My thought is to first drill a small hole to see how much hull thickness I have to work with and then either go with screws into it or threaded inserts epoxied into place. I don't know if I should consider large moly bolts (?) or epoxy the screws in place (if I do that, I would use slotted screws so I could break them out of there someday if I needed to).

Thoughts?

Thanks!

[kananumpua]

Through bolt the bitch on there with over-sized backing plates of aluminum.

[svindigo]

I'd strongly advise against screws or threaded inserts and would go with through bolts and large fender washers and some sealant if in any way possible. I think you would really want to spread the load over as much area as you can via the washers. My $.02.

Ike

[arbarnhart]

It could get tricky; the brackets are pretty close to lining up with the top of the bench. But if through bolts are the answer, then that's what I will do. I have a little wiggle room as far as placement goes.

[arbarnhart]

Well after wiggling and measuring and head scratching, here is what I came up with. Only the top brackets can use through bolts. The bottom ones would come into a sealed off foam filled flotation area. But I can reinforce the top ones heavily on both sides. So that's what I am thinking of doing. I am going to just take the bottom brackets off and put rubber feet on the tubes (and drill a drain hole). I honestly think it only compromises the original design slightly; the force was always on the top ones and some of the other ladders I looked at only attached at the top. Am I nuts? (If "YES" please explain since doing what I propose would only make it like other ladders I looked at).

[sailingdog]

If the top ones are the only ones you can through bolt... then use a decent backing plate for them... since they'll be taking the majority of the load. Make sure you put a washer inside the rubber feet so the tubing doesn't cut through the rubber feet. You might want to go up to 5/16" bolts though...

[Faster]

I'd also make sure you get as many rungs underwater as possible (when deployed) given the dimensions of the ladder esp. if the ladder is to help swimmers get back on board.

If necessary, add steps or grabrails above the ladder on the transom to help accomodate the depth.

[arbarnhart]

Originally Posted by sailingdog

If the top ones are the only ones you can through bolt... then use a decent backing plate for them... since they'll be taking the majority of the load. Make sure you put a washer inside the rubber feet so the tubing doesn't cut through the rubber feet. You might want to go up to 5/16" bolts though...

I have come up with an alternative to the rubber feet. I will use a backing plate that extends to below the bottom brackets and attach them to the backing plate. If I epoxy the backing plate to the hull, I feel really confidant that just having through bolts at the top will be sufficient.

Originally Posted by Faster

I'd also make sure you get as many rungs underwater as possible (when deployed) given the dimensions of the ladder esp. if the ladder is to help swimmers get back on board.

If necessary, add steps or grabrails above the ladder on the transom to help accomodate the depth.

I think I will be okay without extras. I used a regular ladder at the transom to test and my smallest child could get over the transom from the step that was at just about the same height as the swim ladder top step.

[sailingdog]

Originally Posted by arbarnhart

I have come up with an alternative to the rubber feet. I will use a backing plate that extends to below the bottom brackets and attach them to the backing plate. If I epoxy the backing plate to the hull, I feel really confidant that just having through bolts at the top will be sufficient.

Ummm... you do realize that the backing plate goes INSIDE the hull, and acts to spread the load of the bolts out over a larger area of the hull than would otherwise be the case, right???

By definition—if you're epoxying a plate to the outside of the hull—it isn't a backing plate. While your idea of using a mounting plate to attach all the mounting points to and then epoxying it to the hull is a good one, you still need a backing plate for the top bolts—the larger the better.

I think I will be okay without extras. I used a regular ladder at the transom to test and my smallest child could get over the transom from the step that was at just about the same height as the swim ladder top step.

I think his point was more that if the ladder doesn't extend down into the water enough, it will be very, very difficult for you to use it to climb aboard from the water. You generally need to have a minimum of two rungs of the ladder below the water's surface in order for you to get your feet on the bottom rung and climb back aboard.

[arbarnhart]

Yes, sorry, backing plate inside and just more of the same material on the outside which I incorrectly referred to as the same thing.

I will have the 2 rungs in the water. I was answering the concern that I may also need to add one or more above.

I bought 3/8" bolts on my way in this morning.

Please keep the critiques and questions coming; I don't want to screw this up!

Originally Posted by sailingdog

Ummm... you do realize that the backing plate goes INSIDE the hull, and acts to spread the load of the bolts out over a larger area of the hull than would otherwise be the case, right???

By definition—if you're epoxying a plate to the outside of the hull—it isn't a backing plate. While your idea of using a mounting plate to attach all the mounting points to and then epoxying it to the hull is a good one, you still need a backing plate for the top bolts—the larger the better.

I think his point was more that if the ladder doesn't extend down into the water enough, it will be very, very difficult for you to use it to climb aboard from the water. You generally need to have a minimum of two rungs of the ladder below the water's surface in order for you to get your feet on the bottom rung and climb back aboard.