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Old 24-03-2008, 14:44   #1
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Davit pulley

hey everyone,
We have a dinghy davit similar to the one in the picture below. It is very hard for my father and I to pull our dinghy up. I think it has to do with the pulley size. They are very small. I would like to purchase bigger ones. Does anyone know a good website that has quality pulleys? or is there something else i can do to make lifting the dinghly easier?
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Old 24-03-2008, 14:51   #2
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Don't think the pulley size will help a whole lot but you might try increasing the "purchase". Do this by increasing the NUMBER of pulleys on each block. Looks like two on each block so you might want to go to four. That will mean longer lines on each side. Some cruisers, including us have set up small manual trailer winches fixed on the davits to crank in the lines.
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Old 24-03-2008, 19:47   #3
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how would i go about doing this
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Old 24-03-2008, 20:03   #4
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Quote:
how would i go about doing this
You would need to buy them. Just start with getting 3 on each block as 4 per block is going to be really hard to find. As noted size means nothing it's count you want to make bigger. Right now you pull 4 ft of line on each side to raise the dinghy 1 foot (measure it to be sure - honest). If instead of 2 per block it went to 3 then you would pull 6 ft and raise it one foot. That would make it easier to pull but you pull more.

At some point the number of pulleys will add more friction and you no longer get much benefit. After that you get a smaller dinghy or someone stronger.
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Old 24-03-2008, 20:09   #5
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Try using a combination of this

Schaefer Marine Hardware - Detail
and this
Schaefer Marine Hardware - Detail
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Old 25-03-2008, 09:33   #6
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This can be a problem with davits that are produced without keeping the needs of the sailor in mind. Many davit manufacturers will try and fool an unsuspecting sailor into thinking that a 4:1 purchase is enough. The minimum purchase for any davit of any size should be 6:1. If this is only available as an option and is not the standard, I would stay away from that davit manufacturer. Once you get over 300 lbs. the purchase should be increased again to at least 7:1. Over 500 lbs. and you really would need a serious 12:1 block and pulley setup.

Some quality davit manufacturers use these specs as their standard because they know that using the highest quality up-front will always win out over cheap imitations.

The davits pictured are also bent tubes which are fundamentally flawed. Look for a setup that uses cast Almag for modular fittings to avoid bends and welds. Also, as I stated above, do not settle for anything less than 6:1.
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Old 25-03-2008, 12:52   #7
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Garhauer also make good hardware, often cheaper than the other marine suppliers because they don't advertise much, and that really impacts costs.
If you note exactly what you have (i.e. pulley sizes and distances) and call or email any of the marine suppliers, they will probably get back to you in 2-3 days with specifics of what they would recommend and what part numbers to order from them, and of course you can compare recommendations while you shop.

DO NOT try to go cheap with hardware-store pulley blocks, the "marine" quality ones are usually made of different materials to prevent corrosion (if metal) and UV-damage (which eventually gets to all plastics on a boat anyway). The stuff at the hardware stores is generally not suitable for use in damp salt air, or exterior use.
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Old 25-03-2008, 13:53   #8
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Did not mean to infer Schaefer was the blocks to buy. I agree Garhauer are a better option. But the blocks were easier to find on Schaefer's web site to give as an example.
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Old 25-03-2008, 15:58   #9
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Thanks for all the replies. The davits came with the boat when we purchased it used last summer. The previous users kept the outboard attached to the dinghy at all times. I think we will remove it and this should make lifting the dinghy much easier. If it is still difficult we will increase to a 3 block.
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Old 25-03-2008, 16:23   #10
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If you have problems handling the engine I would investigate an engine hoist. This lets you attach the engine to a mounting pad for secure attachment and then lower then engine after the dinghy is deployed. This removes the unbalanced load on the davits and of course reduces the weight. They also work well for lifting supplies from the dinghy to the boat.
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Old 26-03-2008, 15:53   #11
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Model 120 Motor Lift

This model has a safe working load of 120 lbs. and is able to rotate 360 degrees with a teflon sleeve. It comes standardly equipped with a 6:1 block and pulley. The castings are all Almag-35 and the stainless is all 316. It mounts very quickly to any rail, transom or deck with an adjustable rail mount fitting and universal angle base. The unit is also fully removable and is very light.
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Old 26-03-2008, 15:59   #12
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That is a nice setup Ben!
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Old 26-03-2008, 16:05   #13
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Thanks, we put a lot of thought and care into it.
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Old 27-03-2008, 20:10   #14
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That is a very nice setup. I will have to look futher into this.
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Old 28-03-2008, 08:25   #15
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An Adjustable Angle Rotaing Davit

Here is a picture that I just found that really shows off a good 6:1 block and pulley. This model has a safe working load of 200 lbs. for a pair.

Again, all the rotating points, including the compression strut casting at the base, the spline casting at the top and the rail mount are all fitted with Teflon sleeves for minimal friction.

There is a solid bar at all the load points which increase the strength dramatically. Some davit manufactures attempt to impart this strength by adding gussets to join the bars which only serves to combine the existing strength of both tubes. A good system treats each load point separately and so that it adds strength rather than simply giving a false appearance of strength.

Another way that a well designed system adds strength is by having an independent compression strut. When compression struts are welded into place they are simply tying to hold the system together. A free strut is allowed to actually transfer the load down to the base and away from the rail, something that a quality davit is able to do.

Quality davits also have a variety of mounting options so that they can be fitted to any sail or power boat.

If you look for a davit that has some of these features, you will be happy and will not need to upgrade your block pulley system in the future.
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