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Old 19-07-2010, 17:36   #1
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RIB on Davits: To Be, or Not to Be ?

Friends,
As per my latest upgrade (2.9m RIB with console and 15hp 4-stroke) I again need Yours advises.
Mother boat is Colvic Watson 29ft, heavy motorsailor, fitted with pair Whittal Davits. Arms are made of double s/s tubes 1" od. I modify brackets and them looks strong, but as I hung RIB (325 lbs) a lot of flexibility shown.
First solution that came to my head is set of secondary backstays from top of the mast back to the davits. Please advise me how big chance to bring damage to the mast or make other mariners laugh over this idea.
Bigger motherboat or smaller RIB is not answer!
Thank You
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Old 19-07-2010, 18:18   #2
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In 1995 I added two stays from the mizzen of my Morgan Ketch to the aft ends of my davits and, with turnbuckles, I adjusted the tension to compensate for my RIB. I have a triatic from my main mast to the mizzen. I've never had this plan evaluated by a profesisional, but the plan has served me well while cruising from Maine to the Bahamas. I do leave my outboard moter on my dinghy in protected waters, but keep this motor on my main vessel during offshore passages. Take care and joy, Aythya crew
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Old 19-07-2010, 19:03   #3
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Originally Posted by CaptForce View Post
I do leave my outboard moter on my dinghy in protected waters, but keep this motor on my main vessel during offshore passages.
We use a similar system. Anytime we're offshore or in conditions that would stress the davit system, we mount the engine to the pushpit rail. It's a bit of a hassle, but it's nice not to to have to worry about the dink once a breeze sets in.
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Old 19-07-2010, 19:14   #4
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On my CS36M I have a set of Ocean Marine davits. They mount on the transom and stern rail. There was a lot of flex in the stern rail so I attached two stays to the toerails. No more bounce. My RIB with outboard etc. about 300lbs.
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Old 20-07-2010, 05:15   #5
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Thanks for CaptForce, Bash and Vasco.
I will try use this solution this weekend. Looks may be not pretty but I believe it will help.
Thank You
Anton & m/s "Prohor"
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Old 20-07-2010, 07:25   #6
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We have a pair of Simpson Cooney davits on our boat which were installed by the PO (or were part of the original build). Ugly b&astards they are, but they certainly do the job. We leave our 100+ kilo dink plus 54 kilo outboard on them in all weather, including Force 10 gales. They don't flex or budge in the least.

I would be nervous about connecting davits to your mast. You will introduce forces and stresses into your standing rigging which it was not designed to carry. I would think that at the very least, it will bend your mast back and screw up your sail trim. Besides that, you will add a good bit of windage aloft.

I would upgrade my davits, if I were you, rather than that.
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Old 20-07-2010, 08:09   #7
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Dont tie anything to the mast that may fall off the boat........unless its crew......IF your davits wont support the dingy...upgrade them or get a smaller dingy...WE take the engine off when we hoist the dingy as our davits are too small for both....it is a hassle...but we like a big engine on our dingy....maybe without the engine your davits will be able to carry your dingy...ps make sure all the water is out of the thing before hoisting it!
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Old 20-07-2010, 08:19   #8
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A very heavy RIB and engine (325#) on davits? On a 29 foot boat? You're not going out to sea are you? You can't be serious.
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Old 20-07-2010, 08:22   #9
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'just a brief note about my plan and adding stress to the existing rigging or bending the mast and affecing sailshape.... My SS davits are 2" diameter stainless steel pipe with 1" diameter supportive struts triangulated from below. My shrouds from my mizzen are a redundancy as well as an added support for my solar panel. The system is a stiff framework, but with the size and support of my davits, the stress on my rig is not significant. I am putting more eggs in one basket, but I'm attentive to the integirty of the basket. Take care and joy, Aythya crew
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