1989 Trophy 24' - Jetski Lift Project

[LakeMichiganBoater]

So I just purchased a 1989 Bayliner Trophy 24' cuddy cabin and my game plan is to mount and carry my jetski on the rear of it as well as be able to launch it from the boat. Preliminary thoughts are using a "truck crane" and sling while adding a support system inside the rear of the transom. I am a skilled welder and plan to make this structure out of welded steel.

My concern is the weight of the mounts and jetski on the rear of the boat. Being a fiberglass boat there is no real metal structure to weld into, so I think my best bet is to weld a structure that disperses the weight to different parts on the transom and deck. This would be needed for the crane mount also as there is no way just bolting a crane to fiberglass would hold up, so the crane would have to be bolted to the metal structure. I will try to draw this out and upload the picture to give a better idea of what I am thinking.

My big question is how much weight can I put on the top of the transom? the rear deck floor? the sides?

The jetski I would mount is about 3'x7' and weighs under 400lbs (its small). I suspect the metal and crane would add another 100lbs at least.

I know a lot of places sell jetski mounts for the swim deck, but I really do not trust the swim deck to hold 400 pounds and put all that weight pushing into the transom, would much rather mount it on the top rear of the deck.

 

[FunInDuhSun]

I have a friend who has a removable crane mounted on the foredeck of his boat to lift a dinghy on and off the bow. Big difference is that boat is a 41’ Silverton yacht that weighs 25,000 pounds. Remember that all boats are designed for a given weight and buoyancy and changing that significantly can make it unstable or perform poorly.
FWIW, I don’t think your 24 footer is big enough to hang the weight you want to the stern. Guessing the boat is around 4,000 pounds. Adding 400 (10%) to the rear is a LOT. You might want to consider setting it up with a harness to tow your ‘ski behind the boat. I did that to my 34 footer so we can take our Seadoo with us when traveling. I made my own harness based on the Towdster (look it up). It worked really well and we were able to run at any speed without concern.
Now, that said, when towing I always had someone watch the Seadoo to make sure it wasn’t doing anything weird. I also had to add a shutoff valve to the intake; not sure if the Jetski requires that. Whatever you do, think it thru and be careful.

 

[LakeMichiganBoater]

Yeah I do agree with you on the weight issue, something I have been debating.

The main reason I want to do this is for trailering. As I will be trailering this boat everywhere I don't want to have to bring two trailers, would like to get one of my two jetskis on the boat and being they are only 400lbs it may be possible.

 

[FunInDuhSun]

Alright, that’s something you could accomplish just by changing trailers. I’ve seen trailers that carry not only a boat but also a PWC or two. I’ve attached a picture of what I’m talking about. Maybe it’s something you could build yourself with the welding skills! Good luck!

 

[LakeMichiganBoater]

That was something I debated also... not out of the question. Would be tough to fit on the trailer I am using right now though, but maybe Ill explore that option. Don't want another 400lbs on the tongue weight though.

 

[LakeMichiganBoater]

Photo of the trailer situation