Swim platform height

How high is your swim platform above the waterline?

I have to start planning for stuff like this before I start installing structure in the hull. I'd like to make one just like this.



I'm guessing it's about 8" above the waterline. That's the same model boat and the waterline will be the same if not very near the one shown above.

Thanks.....

When lowered, mine is about three inches above water. A soft-bottom dinghy can run its bow on the swim-platform for easy access. Platform is raised to prevent it from being submerged while underway. Engine exhaust is on portside so doesn't enter into platform location. From-water boarding access is from ladder functioning as part of the railing when raised and drops below waterline when deployed.

Dock and hard-body dinghy access is at mid-ship. Decks approximate floating dock height.

Rick,
Ours is right at 14" from water to top surface. It just so happens to be the same as the dock that we stay at. Several things go into the thinking for final height. Do you have exhaust exiting under it? Will it need supports,and if so do they need to be above the waterline where they mount to the transom. Another thing to think about is, how to get back on the deck from the water. In our case a folding stainless steel ladder was added.
Just some thoughts.

Ours is about 12-14 inches above the water.

Thanks Fella's

I think 14" is too high Crusty. Our 10' Walker Bay has Weaver snap davits on it so from my rough guestimate anything over 8" and they won't work with my fat butt in the boat. I will have an exhaust exiting under the platform just about the middle of the transom. It's got one of those flapper thingies on it and gooseneck so it can sit right down to the waterline.

I like the idea of having one that folds up. I even have the hinges for that. Don't know if my backyard eyeball engineering is up to the task or not.

I'd like it to be like the one in the picture. Brackets underneath yes. Our last boat had them mounted to the transom below the waterline with no problems. Boarding latter, yup! Admiral wants a 4 step ladder. Aye aye!

So many things to think of.

Yeah, I just went through the same custom installation process on my boat, and I can tell you that the Krogen Manatee was never intended to have a swim platform.

First, be familiar with the shape and construction of your transom. Is it cored? Where? Is the thickness uniform throughout or is it like a mountain range. Soft spots?

If you've got a thru-transom exhaust, it's beneficial to protect its location if you like it where it is. If it needs raised or relocated to a side exit, now is the time. The platform either has to clear the exhaust by its height or by whatever design needed to provide for its uninhibited flow. I moved my genset from amidships to the veranda and chose to exhaust out the transom as well, so the mod required the same thinking.

Next is to plan the bracket and touch-point locations instead of leaving it to the design of the platform. Most transoms, maybe all transoms are not perfect. The same bracket mounted in one place is an inch lower at the tip when located on the opposite side. Don't end up trying to bush the bracket out with spacers, wedges or washers to make it level. The transom will only be happy with a flat fit. If you have to, space it under the platform but not against the transom. It took three more 25 mile trips to the welding shop to make mine that way and it was well worth it. The location of equipment in your lazarette, transom shape, stringer location, etc. can really ruin your day when it's not planned for when mounting brackets. My transom lifts out of the water on both sides and required six brackets below and two above to equally secure it across its width. If there is anywhere on the platform that unsupported leverage can't be transferred easily to a bracket point, you'll have to make up the difference in thickness or design of the platform and/or material.

I'd say that weight should be considered, but your boat looks like it could swallow up a big platform without much concern unless you plan on moving something else heavy aft. Still, it helps to know the your immersion formula for your boat. Moving my genset aft, adding the platform and brackets, and then a bigger ladder, and maybe a heavier outboard, all of the sudden I'm an inch down in the transom and an inch up in the bow. You get the idea.

I ended up with 8" above the waterline. This seemed to be a good compromise for exhaust clearance, ease of access to the water and dinghy, and still left no substantial step down from my veranda deck height, maybe 1.5 inches. How much your boat squats at what speed might be an issue, so you need to know that too. At 7.5 knots, my platform is getting wet. At 8.5, it may as well be a huge trim tab. When anchored, it takes a pretty steep wake to catch it. The boat simply lifts up before much gets to it. If your transom gets slapped by a wake more than it lifts over it, you may want a higher mount.

The rest of it is choosing the material, trying not to make your platform an obstacle in handling, and to make it something attractive or fitting to your vessel. Best of luck.

Mine is pretty low with brackets underneath. Garelick makes a very nice ladder that mounts under the platform and leaves the top clean.

Wouldn't the height of a swim platform be determined by how high the rear rail is ? If the platform is too low it may be a struggle to board the boat from the platform ??? Mine happens to be same height as the rear deck and its very easy to step from deck to platform or vice a versa

Our platform height is ~12" to the top of the platform with total tankage about 1/3 full (~1000 gallon capacity). Both of us can pull our selves up out of the water on to it. We do have an under the platform folding boarding ladder.

The last 2 are from a Selene. My understanding is that the folding platform was an option that Selene offered for a while

Larry,
Thanks for the picture of the swim platform on the Selene, that's the same one on mine, I just didn't have any clear pictures of it with me. I have removed the block and tackle on mine, makes it a bit cleaner looking.
I'm told this was incorporated to reduce the overall length for those Marinas that actually measure and charge by the foot.

I'm thinkin' a transom door is in our future too. If I put the platform 10" above the waterline it'll be about a 4" step up to the cockpit deck. The 28' version of these boats that have been built, as some have said, have a bit of a tendency to squat at the stern at about 7-1/2 kts dipping the swim platform in the wake. From what I can tell most of those only have about 6" between the waterline & bottom of the swim platform.

Really like the idea of the folding platform. Gotta think on that one!

We have 4 steps between our platform and rear deck.

Our's is 19 inches above the water. Fortunately Weaver makes a step down davit that works well for the inflatable.

Rick,

I measured mine today. At rest the bottom edge is 7 inches off the water. Underway, it's 12-13 inches.

Here's an old, ugly shot after a fishing trip and another from my pre-purchase survey.

...and here is a shot of Al verifying the height the last time he was asked this question.

How do you think I get such accurate measurements?

They don't call it a swim step for nothing!!