Adding an out board crane/davit ideas ?

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dunkelly

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Reaching that age where everything becomes an effort - would like to make /have made a small crane to lift the outboard (4hp) on and off the dinghy . It's only a small 27ft boat . Any ideas or suggestions , anyone done something similar ?
 
Do you need a 4hp O/B?

If you hoist the OB (whichever way) what do you do (normally) with the dinghy. We have a Foldabote which packs flat like a surfboard and we can lash to the stanchions (hoisting it aboard with the spin halyard. I can carry the Foldabote, assembled, single handed (but in Oz they are not cheap).

I imagine you are also following this thread

'Worth upgrading to a 4 stroke o/b?'

I'd suggest davits are a major item of engineering and you will finish up with a lot of weight (dinghy + OB + davits) on the transom. I'd devise a way to hoist the OB using the boom (or a lighter OB).

Jonathan
 
She's a Mac 27 . Plastimo crane . yes that's the sort of thing I had in mind . Not worried about the dinghy ,I have put lifting eyes on and using the spinny halyard I can lift that onto the foredeck easily enough .
 
I made a davit for my wee outboard, a year or two ago. It has made an enormous difference, with the result that we use the outboard much more than previously. We have a stainless taffrail, (think pushpit), and an alloy toerail. Using 25mm x 3mm stainless tube, I bent an angle of approximately 135°, to form the davit. It then can rotate in brackets from the toerail and taffrail. I arranged the stowage mounting for the outboard, on the outside of the taffrail, so that the double purchase tackle on the davit is directly above the outboard. When the davit is swung outboard, it is directly above the dinghy bracket. A simple cleat welded to the davit, for the tackle.
Oh yes, I forgot, we made a webbing lifting harness, which just stays on all the time.
 
I used to use the mainsail boom ..... only bit that was a pain ... boom was shorter than cockpit - so meant O/bd lifted into cockpit - then had to lifted by hand onto the pushpit pad.
I considered adding a short beam to the boom ... to extend it.
 
I wanted to make life easier a few years ago as well... Getting the 2hp stroke back on board was easy but it just wasn't going to happen with a newer 4 stroke 6 hp.

I went for the lifting davit from Force 4 because it looked simpler than the other options.

Force 4 Engine Lifting Davit | Force 4 Chandlery

Screenshot_20230212-104826_Samsung Internet.jpg

Dimensions area on their website. The upper bracket clamped around the pulpit rail and luckily for me, the lower bracket just bolted to the toe rail.

With it fitted in the right place it will lift the engine off the pulpit mounted stowage bracket, swivel and then lower it a pre-determined (with a knot) amount so I can then just get into the dinghy and guide it onto the transom. I don't think I'd manage the bigger engine any other way.

I must admit I did fit a larger block and tackle to the end but that was to make the lifting even easier.
 
We do it a little differently. Rather than lower/lift the engine on and off the dinghy in the water, we simply raise the dinghy with the lifting bridle and the spinnaker halyard. The dinghy rests on the outside of the guardwires. We then pick up the 15hp engine off the stowage bracket with the main halyard and walk it down the side deck and onto the dinghy transom. It doesn't matter how choppy the water is since the dinghy is nice a stable against the guardwires. It needs two people but all very safe and simple with no strain
 
Just in passing - and forgive my ignorance - the "lifting capacity" of that Force Four davit is given as 55kg, and on the same site a (typical?) 4stroke 4hp outboard weighs 27kg . To lift it, as opposed to simply hanging it on the hook would require a force greater than another 27 kg on the other end of the rope. Does that put this motor right at the extreme of the capacity of the davit or does the term (L C, that is) mean that you can safely hang a 55kg load on it and haul away as lustily as you like , and nothing will bend? (Leaving to one side the question of whether all manufacturers, advertisers etc of such gear can be relied on to use the term in that sense).

Second thought :- "on the other end of the rope" is perhaps wrong and/or "a force greater than" likewise. But surely even with the 2:1 effect of the lower pulley, some force needs to be applied in addition to what is required to hold the load suspended. (?)
 
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In a reasonable sea state :
Tie the dinghy fore and aft in the right spot for the swing of the boom.
Use a hoisting tackle that includes a jammer.The mainsheet can be use but that's your control on the boom swing.
Raise outboard in sling over the wires,lower and jam it so that it rests against the hull .
Get in dinghy and guide and lower over transom.
You can place small ply pads on your deck/in cocpit in intermediate rest positions.A larger piece on the floor of the dinghy.
 
As bluerm166 mentions, if you have a system that includes a jammer then you can lower the engine whilst sitting in the dinghy.

As it happens, I did do that (as well as doubling up because for some reason I didn't like the idea of the engine hanging from a single block and tackle)..

20230212_155133.jpg
 
As to the method of attachment to the engine.. don't throw away your old lifejacket with built in harness before getting the sewing machine out and turning the harness part into an engine harness.

20230212_155307.jpg

You'll recognise now where the D-clip came from.
 
NormanS said:
I made a davit for my wee outboard, a year or two ago. It has made an enormous difference, with the result that we use the outboard much more than previously. We have a stainless taffrail, (think pushpit), and an alloy toerail. Using 25mm x 3mm stainless tube, I bent an angle of approximately 135°, to form the davit. It then can rotate in brackets from the toerail and taffrail. I arranged the stowage mounting for the outboard, on the outside of the taffrail, so that the double purchase tackle on the davit is directly above the outboard. When the davit is swung outboard, it is directly above the dinghy bracket. A simple cleat welded to the davit, for the tackle.
Oh yes, I forgot, we made a webbing lifting harness, which just stays on all the time.
Click to expand...
How easy was it to bend the tube ? Did you need to heat /repolish . I have a 4hp 2st do you think 25m! Is strong enough ?
 
No surprise that you've all done it before . Thankyou for the suggestions . Definitely going ahead with one for this season . I like a combination of the force 4 / Plastimo idea, in that I can take it off and stow it easily. Getting the drawing board out now !
 
dunkelly said:
How easy was it to bend the tube ? Did you need to heat /repolish . I have a 4hp 2st do you think 25m! Is strong enough ?
Click to expand...
The strength of the tube required depends on the weight of the outboard, and also crucially the davit radius. The radius that I required was only 480mm, and if I remember correctly, the outboard only weighs 13kg, so yes, 25mm OD x 3mm wall thickness is plenty. I didn't have access to suitable pipe bending equipment, so I did it by "saw draughting", and then welding the saw draughts after bending. A bit of careful grinding, and some rubbing with finer and finer Emery cloth gave an acceptable finish. It's not highly polished, but it's more for function rather than show.
To check the strength of the tube, it's quite easy to take a length of tube, and apply maybe twice the maximum expected load, at the required radius. Or, you can do it by calculation.
 
Many apologies, but I've just checked on the size of tube that I used for my davit.
It was 1" nominal bore, schedule 40 S/S. That is approx 33.1mm od, with a wall thickness of approx 3.3mm.
 
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