Hydraulic Davit Question?

[TMT2]

Any hydraulic davit experts out there? I have a nice set of hydraulic davits on the stern of our Gulfstar M53. They are fully functional but it's time to inspect/test/service the unit. My intent is to hang a 10ft/500 lb Avon Center Console RIB for coastal/inland cruising (25hp Yamaha, plus fuel/battery and steering console unit). Photo of davits is attached. For those who abhor sailing with dinghy on davits - rest easy...we lift the RIB onto the fore-deck for off-shore transit with our mast crane (another CF post).

Ignoring the solar array that I have mounted to the top-side of the davits...does anyone recognize the maker of this davit unit? I have been unable to identify a manufacturer? On a long-shot, perhaps some savvy cruisers have the same set-up? I am comfortable with the solid mounting arrangement as there are large aluminum backer plates on the inside of the transom plus the well-secured locking eyes at the gunnel for secondary stability. What I don't want to do is "test lift" the RIB and blow a lift cylinder creating a hydraulic spill in the water not knowing the lift rating of the unit? Reaching out as a stab in the dark for someone that may be able to ID the unit?

Any help would be appreciated.

TMT2

[sailormed]

No photo

[TMT2]

OK...Figured out that the photo needed to be in "attach files" versus videos.

[TMT2]

Ironic...Just heard from previous owner...custom rig - all the way. Have what I need (based on tube thickness calculation, frame is 800+ lbs/cylinders are compatible/ pump may be undersized - will research) ... but happy to share/describe our setup with others if interested.

TMT2

[Matt Johnson]

Are your solar panels on cabinet slides? Do you have a second row under the upper set?

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[Lepke]

If you're concerned with spills, there are several bio hydraulic oils available. They leave no sheen and are affordable for small users.
Many commercial boats have gone to them. Better commercial suppliers carry them, probably Ebay, too.

[TMT2]

Funjohnson,

The solar panels (4x130W) fold from the outside-in. A king-board "drawer/stainless slide" arrangement provides support for the panel "wings" when deployed.

TMT2


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[TMT2]

Lepke,

Thanks-I didn't know that...I will research your suggestion.

TMT2


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[TMT2]

After many hours of research and a bit of trial and error...the aforementioned davit system lifts and holds our 500 lb AB Rover 340 center console RIB with a Yamaha 25HP 4-Stroke.

For those inclined to opine on davit usage - we do lift the RIB onto the fore-deck for off-shore passage (covered in another thread). I was surprised that the boat didn't "squat" at the stern when I hoisted up 500 lbs! She didn't even flinch.

Now onto the task of eliminating "swing" under the davits. Since the RIB is a center console, cinching/snugging the RIB up to the davits is not an option. Cross ties or ratchet straps won't give me 360 degree rigidity. I am thinking about rigid, adjustable (turn-buckled) aluminum or stainless braces (crossed) to connect from each opposing davit arm to the RIB hull (interior) to prevent swing? Anyone seen, used/have experience or ideas with this technique?...Suggestions?

[jason902]

Rigid supports should work. I'd make sure to bungee the rigid supports to the davit arms, so they are above the boat while the boat is being raised. Then lower them into the boat and secure to the boat.

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[TMT2]

Sharing final photo of my project - appreciate all the help from forum members!

TMT2

[leftbrainstuff]

Does the whole frame and arch pivot? Looks custom.

Looks like a lack of triangulation. Low cycle fatigue will likely be the failure mode. Keep a close check on any cracking or buckling at the hydraulic cylinder attachments. Especially after any sea state is experienced.

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[TMT2]

Leftbrainstuff...The entire davit assembly lowers/raises to/from the waterline. The remote control key fob switch is a nice feature. I agree - I will watch for low-cycle fatigue. I've solved the swing issue with cross-bars and ratchet straps that snug the RIB against the davit arms along the RIB rub rail. We'll give it some coastal testing and make adjustments as we go. Time will tell...perhaps by the time I get it perfect - I will buy a new aluminum RIB, a new 4-stroke... and shave about 170 lbs off of the load.

TMT2