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Old 04-03-2016, 10:14 AM   #21
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I love the dinghy Marty.
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Old 04-03-2016, 12:25 PM   #22
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I love the dinghy Marty.
Thanks Dave .I shopped for a long time for one of these . I bought it in CT. I have a customer that hauls lumber down here to TN and hauls our hardwood flooring back . He threw this dinghy on with a load of lumber .
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Old 04-03-2016, 03:24 PM   #23
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We had a Sea Wise on a 46' trawler we used to own. Absolutely loved it. It was the manual version and was very easy to launch or retrieve the dinghy. It took about 2 minutes to launch and about 3 or 4 minutes to recover the dinghy. We had a 10' RHI with a 15hp 4 stroke. You have easy access to one side of the swim platform. It was great not having to remove the outboard from the dinghy each time. The company was very helpful during the install. It took me about a day to install it.
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Old 04-08-2016, 11:58 AM   #24
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More home-made davits.

I thought I'd share this davit design with you all; it is really simple, cheap (<200$ in materials), and easy to make with standard wood-working tools. We have a 10ft Titan with an aluminum hull and a 5hp Lehr. One person can slide the dinghy up and onto the cradles, with two its really easy. The cradles (1-1/2" thk HDPE) are attached to the aluminum channels with one push-pin each, so can be removed in seconds if desired. Because the cradles sit upright when empty, we have found them to be useful as hand-holds when using the boarding ladder and also getting in-out of the dinghy onto the platform. The 1/4" thk aluminum channels were made from a rectangular extrusion, cut on a bandsaw, then finished with a beltsander. The cradles are a bandsaw-beltsander-router operation. I realized early on how critical the geometry would be, especially the positioning of the hinge point and the non-adjustable stops, so built a wooden version first to get it right. The channels are of course designed to fit our 390, but could actually be simpler on a more standard swim platform (with better access underneath). Their positioning on our boat was partly determined by how far I could reach into the platform through the access ports to hold the back-up plates (with embedded nuts). The two main tie-downs are bow and stern of the dinghy to the edge of the platform (which is fwd of the pivot point), and I have two lines attached to the dinghy handles on the fwd tube that connect to the transom. It is very secure underway, and launches in seconds.
The last photo shows the inspiration behind the cradle profile!
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Old 04-08-2016, 01:41 PM   #25
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That is super cool!
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Old 04-08-2016, 02:15 PM   #26
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Blue...I was going to make those for my boat but depending on transom shape and platform width..the channels can stick out pretty far.

Those are nice...wish I could have.
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Old 04-08-2016, 05:29 PM   #27
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lifting harness

My soon to be new boat has SeaWise Davits on the stern, which I think is great. However, I am also going to want to be able to lift the dinghy up onto the boat deck with the crane. I think the dinghy already has factory eyebolts but I will need to create a lifting harness.

Anyone have any good suggestions on how to design a lifting harness or suggested materials?
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Old 04-08-2016, 05:54 PM   #28
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We have a Nick Jackson davit on our stern. Electric wench and does a great job. Fast up and down. We carry a 12' Boston Whaler on it with a 40 HP merc. Personally I think the boat (too big for a dinghy) and motor are over kill, but it came with our trawler when we purchased her last summer.

The plus to this davit:
Very strong.
Lifts a heavy load securely and fast
Keeps the dinghy weight off the top of the aft deck cover

Disadvantages:
Takes up the swim platform with or without the boat on it.
Expensive to buy and mount

My last boat had a 9 ft Livingston Dinghy on a Weaver davit system.
It worked great!
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Old 04-08-2016, 07:14 PM   #29
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The bottom is about 2 feet off the water...good enough except for breaking waves astern...but no issues so far in any conditions most loopers would do.

The engine needs to have the lifting bridle changed a bit so I can tilt it...in the down position, some waves do hit it.

I should have told my buddy to bend it to 120 degrees, he just assumed 90 degrees and it does droop a few inches with the weight of the motor on the dingy.

It is 2 inch aluminum tubing and I am not sure what schedule...but small gussets will be perfect. The arms seem strong enough...it is the bends that worry me a bit long term. I am going to have him remove 20 degrees from the bends or just bend the tubing a few inches past the 90 bend . This will raise the dingy nearly a foot which will be perfect. 3 inch tubing would be the ticket for crossing an ocean...or go stainless...but for me the 2 inch will do.

The trick with the angle is having the dingy at a good height to put stuff in and out yet when lowered...be close enough to the swim platform to easilt reach and clip on without having to undo the hanging drops.


The supports are not directly over swim platform supports but with a dingy/motor combo under 200 pounds...didn't see it as an issue...of course the swim platform is critical if through bolting and strength aren't there.
Are the upper clevis pins going through the tubing? If so, that would weaken the tubing somewhat. By making the clevis pins go outside the vertical tubing, it would still be full strength right to the curve.

Also, a brace would add more strength than a gusset.

Still, pretty good solution for carrying the dink!

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Old 04-08-2016, 07:23 PM   #30
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We also have Nick Jackson davit system on our new boat but we haven't decided if we like it or not. As S41 says, the weight is not on the lid which we do like. Our last boat (a sundeck trawler) had Roskelly Olson ST-275 transom davits and we really liked the system but it was tough for my wife to use. I thought it was pretty easy to deploy and retrieve.
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Old 04-08-2016, 08:33 PM   #31
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Are the upper clevis pins going through the tubing? If so, that would weaken the tubing somewhat. By making the clevis pins go outside the vertical tubing, it would still be full strength right to the curve.

Also, a brace would add more strength than a gusset.

Still, pretty good solution for carrying the dink!

Stu
OK...I'll bite because I am only a backyard guy and no engineer...

Do you have any numbers to show how the holes reduced any required strength? (webbed designs, trussing, etc...are all designs with material removed and occur without serious loss of strength)

And depending on the gusset size and brace design...there is no way to say one would be stronger than the other.

But thanks...it is OK and could be better in other respects.
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Old 04-08-2016, 09:20 PM   #32
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You are right, to a degree.

A gusset is typically shorter than a brace, and the span is what makes the difference.

Drilling a hole in a cylinder removes metal, and introduces a weak point. Whether the weak point is enough to introduce a stress fracture, I don't know. I don't know the tubing size nor its alloy.

As long as it works, it works...
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Old 04-10-2016, 09:00 AM   #33
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Lifting harness ideas...

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Originally Posted by dhays View Post
My soon to be new boat has SeaWise Davits on the stern, which I think is great. However, I am also going to want to be able to lift the dinghy up onto the boat deck with the crane. I think the dinghy already has factory eyebolts but I will need to create a lifting harness.

Anyone have any good suggestions on how to design a lifting harness or suggested materials?
I'm going to assume there's two lift points at the transom and one near the bow of the dinghy. You could take three ratcheting cargo straps, one on each eyebolt, and run them to a single ring. Shorten up on the straps until the ring is over a point approx. 3/4 of the way to the stern, and the ring is at the height you'd like. When the dinghy can be lifted by the ring and remain level, the strap lengths are correct. You could also use chain and s-hooks to determine the leg lengths, but either way it's just a trial and error thing to find that sweet spot over the CG of
your particular dinghy. I guess there's three choices for the bridle material...chain, webbing straps, or rope. Personally I'd go for the webbing straps or rope and avoid chain......no experience with hoisting dinghies but have moored close to those with chain hoists, and been woken up by the noisy chain when they make the early-morning trip ashore with the dog
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Old 04-10-2016, 10:38 AM   #34
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I'm going to assume there's two lift points at the transom and one near the bow of the dinghy. You could take three ratcheting cargo straps, one on each eyebolt, and run them to a single ring. Shorten up on the straps until the ring is over a point approx. 3/4 of the way to the stern, and the ring is at the height you'd like. When the dinghy can be lifted by the ring and remain level, the strap lengths are correct. You could also use chain and s-hooks to determine the leg lengths, but either way it's just a trial and error thing to find that sweet spot over the CG of
your particular dinghy. I guess there's three choices for the bridle material...chain, webbing straps, or rope. Personally I'd go for the webbing straps or rope and avoid chain......no experience with hoisting dinghies but have moored close to those with chain hoists, and been woken up by the noisy chain when they make the early-morning trip ashore with the dog
Great idea on using the straps to determine the proper location.

For the harness I was thinking of using some Amsteel line that I have. I can splice SS hooks to the ends and bring them together and splice each to a SS ring. At least that was the best idea I could come up with.
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Old 04-10-2016, 12:03 PM   #35
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Great idea on using the straps to determine the proper location.

For the harness I was thinking of using some Amsteel line that I have. I can splice SS hooks to the ends and bring them together and splice each to a SS ring. At least that was the best idea I could come up with.
That's what I have. Works just fine.
I used spring loaded carabineer type hooks though.
My amsteel is 5/16" which is way oversized for a 600# dink but I wanted some substance to hang onto.
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Old 04-10-2016, 12:32 PM   #36
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That's what I have. Works just fine.
I used spring loaded carabineer type hooks though.
My amsteel is 5/16" which is way oversized for a 600# dink but I wanted some substance to hang onto.
Yeah, the Amsteel is so strong that if sized appropriately it is too small to handle. I have Amsteel that I have used to make soft shackles for the boat. I think I have enough for a harness.
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