Swim Platform Design

[Acadia]

Hi,

I am slowly designing a fold down swim platform for my 85 Hunter 40 that I will probably build this winter. I think I have my design put together but always looking to refine it. The picture I attached is what I have in mind with the exception that it will be external and made from wood. For the steps going up, still deciding on those. I have the room inside the hull to cut steps into the back, but not sure I want to get that involved.

Does anyone here have a fold down swim platform willing to share pics and design features?

Platform height -- For those who have or have used a platform, folding or not, how high from water level is it? Given that my design will be folding, it could probably be lower but either way I will build it above the squat line under power. I'm thinking around the 12" mark. Our sailing is mostly coastal cruising.

Stainless steel -- The Hinge will be made of 4" 1/4" Stainless angle. I am thinking of going with 316. Is there any reason I should go with 304? Price diff is not much.

Steps-- This is where the bad drawing comes into play. The drawing is supposed to give you a visual of what I am about to describe, hopefully not more confusing. I will only finalize the step design once I have installed the platform. At the very least I could use the small bolted on steps that are on the boat now. But we would like something more comfortable to climb. So the idea is to build steps that would partially extend outside and inside relative to the hull surface. There would be two rectangular inserts glassed in. Combined with the outer portion of the step, the insert would allow us to have the majority of our foot in contact with the step while climbing aboard.

I was thinking of glassing in additional vertical supports on either side of the stairs (refer to bad drawing). But I'm wondering if it's overkill given that the inserts will have both a vertical and horizontal component perpendicular to the once mostly flat hull.

I would appreciate your input that might improve my design or point out any potential flaws. Not going to start this for a few months so got lots of time to fine tune it.

I was inspired by what this skilled individual did on his Morgan. My project will not be as ambitious but what a great job he did on that boat!!

Morgan 43 Sailboat Upgrades

Thanks!!

[James S]

I not sure if you would need the internal supports as long as the step "inserts" are glassed in on all sides (they could be prefabricated off the boat) but that would depend, you could add them if it has much flex.
But if your going to go to that much trouble (which i would) I would take the extra step and recess the platform as well (when closed) giving you a wonderfully flush transom face.
The entire thing (step and folding platform assembly) could be fabricated off the boat in the comfort of your garage or workshop...then when you get to the boat...you make the rectangular cut out and glass the whole thing in.

As far as the height from the water goes....I'd consider dropping it to about 8" off the water.

[Acadia]

Originally Posted by James S

But if your going to go to that much trouble (which i would) I would take the extra step and recess the platform as well (when closed) giving you a wonderfully flush transom face.

I agree that looks very nice. The problem with this is that although I have some room behind the transom, I don't have enough for that design. In fact the top step might be more out than in. Also, I would like a slightly bigger platform. The deck will be wooden slats so this way if a wake comes toward the back it won't push the platform up as violently (in theory).

So I hope in the end it does not look too bad on the back of the boat. I guess we'll see. Then again I can handle a little "look bad" if there is lot's of "remember how we use to hang off the back trying to get aboard"

I'll post pics whenever I do get around to building it.

Thanks James

[Jim Cate]

G'Day James,

Query: Where are/is the backstay chainplate/s (if your model Hunter has one).

On many boats the transom is highly stressed, so that the cut-outs for the steps would have to be well reinforced. Further I surely wouldn't wand to make a cutout as big as the platform as suggested above, despite its potential esthetic appeal.

Cheers,

Jim and Ann s/v Insatiable II lying Cairns, Qld, Oz

[Acadia]

The backstay is split and won't be near anything that I will add to the boat.

As for the cutouts They won't be as big as I drew on the sketch. I drew that rather quickly to try and give a better picture of what I was thinking. Looking at it now, those cutouts look rather HUGE. I would basically cut them out wide enough for the steps maybe 16" at the most and and less on the height. In fact, I just started thinking of designing flip down steps. Not sure if they would look odd or not but might be an option as well.

Thanks

[Winter River]

Our boat came with a simple fold-up swim platform that works great. There is a single step cut into the transom. It's probably more basic than what you're thinking of.



The platform is large enough for more than one person to hang out on comfortably. When down, it's just high enough to slip the dinghy under, which makes getting on and off very easy. The telescoping swim ladder folds first, on top of the platform, then the platform folds up to the transom.

[Acadia]

Winter River, Thanks for sharing the pics!! Now I have something to show my wife other than my bad drawings.

One question about the height. I can see that the level of your platform would make it easy to get in the dinghy but how is it to climb out of the water from the folding ladder? We go in the water a fair bit and I want to make sure that I don't make it more difficult for ourselves.

[Winter River]

Glad you like the pics, Acadia. The telescoping ladder is 4 rungs, with two above and two below the water. It's quite easy to climb up. The bottom step is low enough to use when getting out of a kayak. You could always size the ladder to be sure it works for you.

This is the best pic I could find of the ladder:



The line on the right is tying the kid to the boat. The one flopping on the left allows us to pull the ladder down from the water -- not that we'd ever just jump in without putting the ladder down first

[MarkJ]

Originally Posted by Winter River

The line on the right is tying the kid to the boat.

That looks like a whole lot of fun!

Great photo!!!

[Acadia]

I agree and I'll be posting my photos when I complete my project this winter. My design keeps evolving thanks in part to some of the posts on this tread.

[Winter River]

Thanks, Mark. I love the look of pure joy.

I found a boring picture of the ladder:



Good luck with your project, Acadia. I'm looking forward to seeing your final solution.

[velero]

Winter River what the diameter of the tubing on your arch? 1.5 or 1.75?

[capt_douglas]

Guests seem to have the toughest time when they're about half way out of the water. I don't see any grab handles in your design so you might want to give that some thought.

The diameter and style of the tubing can cause problems. Too small a diameter and it hurts your feet. If the tubing isn't sufficiently skidproof, then feet can easily slip off. The telescoping ladder with the black footrests looks like a good design.

The hinge where the tubing hangs down will be under considerable pressure and the user tries to stand up so you might want to look at that as well.

Finally, you might want to make the platform about dinghy height so that you can easily go from platform to tender and back.

[Winter River]

Velero, it's a Wells Marine arch. The web site says it's 1.5". Wells Marine Arch This pic from their site is our boat, before a previous owner added the swim platform and step.



Capt_douglas, I agree with the handhold issue. You'd think we could just grab the line that limits the platform's drop. This works if you're standing on the ladder, but if you grab it from the dinghy the platform begins to fold up away from you. The platform itself provides lots of good places to grab. The easiest way to get off a dinghy is to pull it under the platform a bit, stand up, and sit directly on the platform.

As you suspect, the ladder is a good design, easy to climb in bare feet.

[SV.Maverick]

Acadia, Did you get to the swim platform this winter? I would love to see some pics if you did. I am in the process of trying to come up with something for the back of my Islander 36 like that but I have much less space to work with. I am just looking at this point for any ideas as the transom of the Islander 36 is on the small side but I feel sure someone out there has done it on a boat like this.