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Old 05-14-2017, 10:53 PM   #1
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Dinghy up level with flybridge

All,

I'm adding some dinghy davits to my 40ft Mainship and would like some feedback if it's a good idea.

I'm going to mount the davits on the aft flybridge, that will overhand the swim platform and bring the dinghy up to the level of the flybridge.

Advantage is that it's totally out of the way. Can get on the swim platform and it's above. Looking out the aft area from the lower helm, and it's above. Looking aft from the flybridge and it's below, but might block a bit trying to look down from the back.

With the same davits I could just hold it on the swim platform and tie it to the cleats to keep it from swinging aft. A bit of a crude drawing, but the idea is there.

Thoughts?

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Old 05-14-2017, 10:59 PM   #2
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I would be concerned that, unless you stabilize the dinghy against port/starboard motion, the boat's roll, which is more pronounced at that height, will be exacerbated by the motion of the dinghy, which in turn will increase the dinghy's sideways movement. If you hit a resonant frequency . . .
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Old 05-15-2017, 01:13 AM   #3
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Clipper 40s(sold in US as Mariner, but ? with this) have an OEM rack for the dinghy, cantilevered off the aft FB. As Mainship don`t have this as OEM you`d need to check support strength. Clipper fit a Davico crane to lift/launch the dinghy, pipe supported to the lower deck. This would have the dinghy locked in place, no movement.
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Old 05-15-2017, 01:13 AM   #4
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The dingy will swing side to side no matter where you mount it. I use two tye down straps with ratchet tighteners in a cross pattern from bow of dingy to opposite davit and stern of dingy to opposite davit and that holds it in place with very little swing.
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Old 05-15-2017, 05:22 AM   #5
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Thx,

Good comments. I saw a similar solution on line today. Looks like they have two arms that support the dinghy on a small platform, and got the dinghy and motor up there.

I sure like it out of the way.

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Old 05-16-2017, 09:26 PM   #6
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All,

I'm adding some dinghy davits to my 40ft Mainship and would like some feedback if it's a good idea.

I'm going to mount the davits on the aft flybridge, that will overhand the swim platform and bring the dinghy up to the level of the flybridge.

Advantage is that it's totally out of the way. Can get on the swim platform and it's above. Looking out the aft area from the lower helm, and it's above. Looking aft from the flybridge and it's below, but might block a bit trying to look down from the back.

With the same davits I could just hold it on the swim platform and tie it to the cleats to keep it from swinging aft. A bit of a crude drawing, but the idea is there.

Thoughts?


Structural issues ...... just be sure the thing will not collapse. I assume your davits are powered and not manual. Manual will be a big PITA. Oh-- the picture shown has the dinghy well inside of the swim platform, so much so that lowering/retrieving will find that platform to be a good size obstruction.
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Old 05-16-2017, 09:37 PM   #7
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Ill have to take a pic of my monstrosity.
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Old 05-16-2017, 11:08 PM   #8
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I cant see how the fly bridge lip will be strong enough to mount the 2 davits without a massive amount of redesign and added strengthening . The mechanical advantage on the base bolts of the davits is your biggest concern .
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Old 05-16-2017, 11:14 PM   #9
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I cant see how the fly bridge lip will be strong enough to mount the 2 davits without a massive amount of redesign and added strengthening . The mechanical advantage on the base bolts of the davits is your biggest concern .
Good point, it's a matter of how big a back plate under the deck would work. I'll have a engineer friend of mine check it out.

The one with the supports a few posts up could be an idea.
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Old 05-16-2017, 11:29 PM   #10
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Good point, it's a matter of how big a back plate under the deck would work. I'll have a engineer friend of mine check it out.

The one with the supports a few posts up could be an idea.

Im a design engineer

Its not what size plate under the davit its whats holding the davit up from underneath and where that extra weight is been transferred to . The weight should be transferred vertically to the deck but whats holding the deck up

We make a living from making simple things hard

I did look at doing the same on my IG32 the dingy gets in the way of casting when fishing but I binned the idea too much heart ache for so little gain
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Old 05-17-2017, 12:43 AM   #11
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It looks to me raising and lowering past the swim platform is going to be problematic, needing someone down there "helping" with the dingy. If you do motorize it, have a remote switch so you don't necessarily need two people.
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Old 05-17-2017, 12:54 AM   #12
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Here is an advert for a Clipper 40 with the dinghy where you would like it. They use a crane, supported through the FB to the lower deck, to lift/lower it. Go through the pics, some may be helpful. Used Clipper 40 for Sale | Boats For Sale | Yachthub. Note Clipper 40s are built solid, like the proverbial brick outhouse.
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Old 05-17-2017, 01:03 AM   #13
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Here is an advert for a Clipper 40 with the dinghy where you would like it. They use a crane, supported through the FB to the lower deck, to lift/lower it. Go through the pics, some may be helpful. Used Clipper 40 for Sale | Boats For Sale | Yachthub. Note Clipper 40s are built solid, like the proverbial brick outhouse.

So very tempting
Bruce he will take less I have already asked LOL
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Old 05-17-2017, 02:39 AM   #14
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So very tempting
Bruce he will take less I have already asked LOL
I know, met him when I inspected, interesting seller. That dinghy hadn`t been used for a long while, but it was staying put,and the boat wasn`t bending under the weight. I`m thinking it could be picked from the side and swung into position using the crane.
My St. Croix crane(manual) picks up on the side, dinghy goes on the aft FB, no aft overhang, not much room on the FB either. I think we`re keeping the IG.
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Old 05-17-2017, 03:08 AM   #15
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I know, met him when I inspected, interesting seller. That dinghy hadn`t been used for a long while, but it was staying put,and the boat wasn`t bending under the weight. I`m thinking it could be picked from the side and swung into position using the crane.
My St. Croix crane(manual) picks up on the side, dinghy goes on the aft FB, no aft overhang, not much room on the FB either. I think we`re keeping the IG.


We should go 1/2 in the Clipper 40 and then we would both be happy
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Old 05-17-2017, 09:34 AM   #16
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Here is an advert for a Clipper 40 with the dinghy where you would like it. They use a crane, supported through the FB to the lower deck, to lift/lower it. Go through the pics, some may be helpful. Used Clipper 40 for Sale | Boats For Sale | Yachthub. Note Clipper 40s are built solid, like the proverbial brick outhouse.

Didn't follow your posted URLs but a crane is the way to go. I installed a crane on my boat (used from Sailorman in Ft. Lauderdale) right after I purchased the boat. I also fabricated aluminum chocks that I mounted onto our front deck in a manner to that didn't block an exit hatch. My dinghy sits perpendicular to the boat's rhumb line. The base of the crane is plate mounted to the deck along with a 4" aluminum support pipe that passes through the deck into an interior closet. I mounted a base for the pipe which absorbs the mechanical vertical forces; the deck plate transfers the horizontal forces to the deck proper.

I pick the dinghy up, fully loaded including the outboard, swing the crane over the water and lower the dink into it. REverse process for retrieving it.

I strongly prefer a davit crane.........but I am not the one with the OP's problem.
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Old 05-17-2017, 07:36 PM   #17
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foggysail,on the advice of an engineer boat neighbour I have not supported the St. Croix from FB to main deck. We lift 30kg, the mounting is pretty much over the side house "wall", there is a large plate under the FB to distribute load, and the plate has a turn down screwed to the house "wall" longitudinal timber. The Europa design provides a support right opposite the mounting. And the "mast" tube is bracketed to the railings, as St Croix suggest, using fittings they provide.
I`m a little nervous about it and know it could be controversial, but deflection is minimal under load, I think it works, but I`ll be watching it.
But no way would I mount davits as the OP originally considered, the aft FB deck would likely fail. The link was to provide the OP pics of how Clipper did it, OEM.
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Old 05-17-2017, 08:44 PM   #18
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FlyWright sans dinghy?:



Most elegant, dinghy atop master cabin, with a crane:

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Old 05-17-2017, 09:11 PM   #19
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My setup.
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Old 05-17-2017, 09:13 PM   #20
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Im a design engineer

Its not what size plate under the davit its whats holding the davit up from underneath and where that extra weight is been transferred to . The weight should be transferred vertically to the deck but whats holding the deck up

We make a living from making simple things hard

I did look at doing the same on my IG32 the dingy gets in the way of casting when fishing but I binned the idea too much heart ache for so little gain
Geeze from an engineer! Give me more thoughts. I'd love to hear ideas from you, thx.
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