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Old 09-08-2008, 20:34   #1
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dinghy davits

I am thinking of engineering some dinghy davits out of the stuff they use for chain link fences.

Discuss.
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Old 09-08-2008, 20:49   #2
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I built oars out of the toprail about 1-1/4" plenty stout. after 2 yrs showing considerable rust around all cuts and holes drilled. Still working admirably though. would you regalvanize or paint after cutting drillling and welding?
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Old 10-08-2008, 02:56   #3
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In my gallery is a rough drawing of what I am thinking.

I will be cutting so I suppose some kind of sealant is in order- but no welding. I am not sure how to handle the end- where I will attach line or whatever- but the rest can be done with off-the-shelf accessories.

A) corner piece
B) pipe
C) this is a clamp and the plus sign is a bolt that goes through it
D) is an end cap with a little blade piece with a hole in it- the bolt in C goes through the hole
E) more pipe

The unlabeled pieces are just a mirror of the top.

I'll have two of them and both will be able to rotate on that vertical axis so I can move them around. I might need some sort of easily attach and removable cross piece so I can lock them together when I want to. I also think I could add an assembly on top that I could mount solar panels to...

I am planning on cutting through the fiberglass and mounting them against the inside of the stern.

Like I said I still need a solution for the ends where the dinghy will hang- but the other stuff will cost about 30 bucks...
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Old 10-08-2008, 07:34   #4
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Personally, whenever adding equipment or making improvements to my boat, I try to keep one eye looking towards future resale value.

That eye is blinking furiously when reading your description.
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Old 10-08-2008, 14:01   #5
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Yeah, I got a *LOT* of that while shopping.

Ultimately I am buying the boat as an investment in my TIME/HAPPINESS over the next few years. Not a financial investment. Every time the subject came up it was a place where long-term-theoretical-resale-value was put up against my happiness/satisfaction.

I am poor. Making this all work is a huuuuge challenge. I am not going to "work another year". New davit systems are way out of my price range. Used davit systems are still way out of my price range. This will/should get the job done- giving me all the convenience of the expensive systems without the cost. It will be a little heavier but that weight difference won't even approach the weight of a bigger outboard...

Besides, most of the "you have to consider resale value" arguments use this theoretical cherry state for comparison. This boat will not be "restored" ever. Any future buyer will likely be somebody like me- out to get the most boat and boat related functionality they possibly can for the available dollar.

I think I am rambling now.
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Old 10-08-2008, 14:22   #6
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Ultimately I am buying the boat as an investment in my TIME/HAPPINESS over the next few years. Not a financial investment. Every time the subject came up it was a place where long-term-theoretical-resale-value was put up against my happiness/satisfaction.
I agree with you. When I bought my boat the last thing I was worried about was resale value. I figured if I could not sell or donate the boat I will just scuttle her. The bottom line is to make the boat useable and comfortable for me at an affordable price.
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Old 10-08-2008, 14:31   #7
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my first boat was named forsailbyowner and thats exactly how I built her FOR SAILING BY THE OWNER
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Old 10-08-2008, 14:35   #8
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Jack,

Not a solution I'd do myself, but I can understand where you're coming from. Here are a few observations, based on my experience with Kato davits on my boat.

You'll definitely need cross bracing near the end of the arms, maybe 3/4 of the way out. The whole thing needs to be quite rigid, because it will be subjected to a variety of up and down and sideways forces.

You'll probably be using 4:1 and/or 6:1 blocks and tackle to hoist the dinghy. The topmost blocks could be shackled to eyebolts installed at the ends of the arms. You'll need to haul the dinghy up as far as possible to avoid swinging. When the dinghy is up tight in the blocks, the braces you show between the uprights and the horizontal arms look like they may interfere with your dinghy.

The uprights on my davits are attached to the pushpit. The base of each is attached by a base flange, through-bolted through the caprail and fiberglass deck. A SS strap was added adjacent to each upright from the top pushpit rail down to the inside of the cockpit to add bracing to support the pushpit.

Finally, it helps to cross brace the dinghy itself. I have two nylon webbing straps with ratcheting mechanisms for tightening. One end is attached to the base of a pushpit stanchion, and the other attaches to the dinghy with an "S" hook. The two straps criss-cross each other and serve to pull the dink in toward the stern, as well as keeping it from swinging and swaying. You could do the same thing for cheap with polyester line and a trucker's hitch.

Hope this is helpful.
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Old 11-08-2008, 03:00   #9
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Wooden davits...

The WEST book that I have claims that well engineered WEST glued and coated wood has strength similar to aluminium and I have seen nothing to make me doubt this claim.

I'm planning to make my davits out of wood, mostly 75 x 75 pine, rounded and tapered with 8M bolts and 12mm ply gussets, bolted to a plate welded to the deck and the 38mm SS tube pushpit. The whole contraption to be removable.

I'm even hoping to extend it all skyward with provision for mounting solar panels, antennae, radar, wind generators and the like.

The advantage of wood is that if I overdo it and it breaks I should get lots of warning and can rebuild easily.
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Old 11-08-2008, 05:49   #10
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Here is a link to guy who made wooden davits by laminating thin strips of wood and fiberglass roving.

Improvements made to Destiny Calls - Wooden davits
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Old 11-08-2008, 09:12   #11
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I have never seen a davit made of aluminium, all I have ever seen are made of stainless.
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Old 11-08-2008, 23:25   #12
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I actually read an article in... a magazine... if anybody cares I will look it up... But it was how to make custom wood davits for under 200 bucks. The ones the guy made were gorgeous and I am sure very strong.

However, the article assumed access to a robust woodshop and a pretty solid wood working skill set. I barely survived making spreaders, had access to a shop, help from a guy who knows what he is doing, and they still have like 15 problems that I know of!
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Old 12-08-2008, 08:42   #13
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I'm a little unclear whether you are talking about aluminum rail, or galvanized. I don't think aluminum would be bad if you can size it to be strong enough, a lot of the dive boats I used to work on used aluminum 'speed rail' to build large awning/biminis. If it's galvanized pipe like I thought that you meant, you will likely regret it when your davits start bleeding rust all over the back of your boat.
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Old 12-08-2008, 09:24   #14
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dinghy davits idea

here's a thought, and one i am seriously considering for my 36' gulfstar:

instead of making your up-and-out supports 90 degrees from each other with a 45 degree brace for strength, could you instead take a full length of the pipe to a pipe bender and have him bend your vertical/horizontal support up and out so each support forms a nice rounded/inverted 'L'? with the proper size pipe stock there should be no need for a support brace.

if this could be done then you might have stronger supports since there would be no joints, it would be easier to fabricate and install and it might even be more aesthetically pleasing (i appreciate that this last bit is not important to you).

what do you think?
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Old 12-08-2008, 18:35   #15
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Its not that the aesthetics are not important to me. It is they are secondary to the functionality. At the moment it looks like my choices are ugly or nothing.

Anyway, I actually started my research by looking into having pipe bent. The setup cost alone was over 100 bucks. Then there were bending charges. Then the pipe itself. My rough guesstimate from that was that it would cost about 600 bucks.

The stuff I am looking at is not aluminum. While I am concerned about rust I have to say that I've never seen horrific rust stains around chain link fence posts... And while what I am building is certainly second class- I am not one of those people that doesn't maintain their toys. I would like to think that I won't be the guy with the stains...

Anyway, davit project is on hold for about a week probably so I could still get talked out of this path. I am wrapping up the shelves in the hanging locker and playing with my many dinghies now. Yeah, I said "many" dingies. There are three. I will post ALL about that in another thread when I have a few minutes free.

Anyway, thanks all- keep it coming. My big concerns are things like "will this cause damage to the boat?" "will this cause me to lose the dinghy?" and then my small concerns are "without spending too much more money- can I make this more elegant (er?)"
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