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Already There 11-29-2012 05:55 PM

Dinghy davit help
 
Hello all,
What would be a good set up for my davits to lift a 75 lb dinghy with a 40 lb outboard? I have the davits, but no lifting blocks or lines/cleats. The davits are basic stainless double tubes with two holes out at the lifting end of each one. Thanks in advance for any info. :eek:

Seaduction 11-29-2012 06:55 PM

Re: Dinghy davit help
 
6:1 purchase blocks at the end of each davit.:)

Already There 11-29-2012 11:20 PM

Re: Dinghy davit help
 
Thanks Seaduction. I will get those blocks and get busy...

chef2sail 11-30-2012 12:42 AM

Re: Dinghy davit help
 
4 blocks to make -6:1 purchase.... blocks, 2 with cam cleats,2 with carabeener clips
2 marlon horn cleats attached to the arms of the davits
2- web staps in the shape of a triangle with each strap having at its corners
a SS circle, 2 corners have carabeener clips to clip on dinghy attach ponts
the last circle is for the davit carabeener to attach to.
The davits should have a cross bar to maintain stability if possible
Lots of line

The davits need plenty of support with backing plates as well as side struts if possible

We have Garhauer davits. If you go buy their picture you will be fine.


Product Specs

Dave

Stumble 11-30-2012 12:54 AM

Re: Dinghy davit help
 
It might just be me, but I think 6:1 is way more purchase than you need for a dinghy this size, and it adds more friction than advantage. If you assume each davit carries 1/2 the weight, and the boat weight 70lbs, each davit is only carrying 35lbs or so. For this I think a 2:1 is more than acceptable.

chef2sail 11-30-2012 05:17 AM

Re: Dinghy davit help
 
Quote:

It might just be me, but I think 6:1 is way more purchase than you need for a dinghy this size, and it adds more friction than advantage. If you assume each davit carries 1/2 the weight, and the boat weight 70lbs, each davit is only carrying 35lbs or so. For this I think a 2:1 is more than acceptable
Do you have davits? If you do I dont think you would be happy with 2:1.

Dont make this anymore difficult than it has to be. It doesnt add more friction, it makes it a greater advatage.

The weight wont be evenky distributed as the engine is one the rear of the dinghy. So right there thats 75lbs on the rear, one one davit arm. Add 8.5 lbs times the number of gallons either in the integral engine tank or external tank. The dinghy is usually not dry or empty so add for water in it and any stuff like oars, vests etc. Lastly there are are times you want to tillt it down to drain water so more weight will be on on the engine end. In addition sopme day you may ewant to increase the size of the dinghy ( weight) or/ and engine ( weight) again. If you are pulling the dinghy up by yourself, usually you pull on one line at a time so the weight is borne by one line.

A lot of the of the better systems use 4:1 with an upgrade option to 6:1. You proabably can get by with 4:1 but why strain Your choice.

Dave

chucklesR 11-30-2012 08:39 AM

Re: Dinghy davit help
 
I agree 6:1 - make life easy.
My RIB weighs 115 pounds, the engine adds 55 and the crap in the dinghy adds another 15 or so.

Then again, if you are raising the dinghy yourself going from side to side you are NOT only pulling up 1/2 the weight. It doesn't work like that as it's not balanced in the middle. I can pull it up hand over hand, but the wife can't.
For a extra 20 bucks per block and bit more rope keep life easy, your back will appreciate it, and so will your spouse.

pdqaltair 11-30-2012 09:55 AM

Re: Dinghy davit help
 
6:1. The guy suggesting 2:1 certainly has titanium guns and no arthritis in his fingers. He also made a calculation error. With a 40# outboard hanging over the end (think leverage), a bit of water, and perhaps a PFD and some oars (yup, stuff gets left in there sometimes), the load on the aft end is closer to 100#. Use small line (gloves) and ball bearing blocks to minimize friction. I supose you could go lighter in the bow, but why bother.

This is what I did (up-grade from the original 3:1) and I love it, wouldn't do anything different. Basically a dingy mainsheet system (there are horn cleats to lock it off at the foot of the davits; the cam cleats REALLY help by providing a rest and allow you to work one end at a time)
Sail Delmarva: Better Purchase for Dingy Davits
Remember to look up the lacing pattern for 6:1 blocks; it is not obvious and doing it wrong leads to high friction. Note in the picture they are rotated 90 degrees from each other, which is essential.

Also, remember to trice-up. You may need some eyes and cleats for that.
Sail Delmarva: All Triced-Up

Stumble 11-30-2012 01:00 PM

Re: Dinghy davit help
 
I would like to appologize, I completely missed the OP referencing the 40lb outboard on the dinghy. Certainly as weight goes up purchase goes up until you find an amount of purchase that is comfortable for you.

pdqaltair 11-30-2012 02:15 PM

Re: Dinghy davit help
 
I figured you might just be a lot stronger than me. Very plausible!


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