Davits yes or no

[Laminar Flow]

Hi, I've owned two boats with davits. A few things to consider: The bottom of the dinghy should be at least 4' over the water, especially in a short steep sea to prevent it from being hit or touching; I've experienced that particular situation. With 4'+ clearance I've crossed oceans. The dinghy should, preferably, not be longer than the transom is wide and certainly not wider than the boat (hardly a problem in your case). Otherwise, there will be lots of fun as it catches on other boats, pilings and likes to scrape along the quay or lock walls (inflatables with the two pontoon extensions sticking out are particularly notorious for that). Mooring in a Med style situation you have to drop the dinghy before backing in. We prefer to go stern to as our bow is 2m off the water and my wife refuses to join the alpine troops and to learn how to rapel. However, we have damaged our rudder backing in when we could not see the bottom. I like the shippy look of davits and would have them on our current boat if it were not for the inconvenience when going stern to. They are also a handy place to store surfboards and other similarly awkward bits while at sea.
Best, A.

 

[dunedin]

There are also 100Kg ones, which for just a 2.7m aluminium rib and a small o/b would be fine

Plastimo Stainless Steel 100kg Davits - Davits / Dinghy Rings - Discount Marine Chandlery and Sailing Equipment. Bargain Boat Spares and Clothing

That’s what we have. Have been brilliant for our type of sailing, when dinghy gets used a lot. We have a 2.7m airdeck with lightweight 2hp two stroke on a (wide sterner) 38 footer. Needed to reinforce stern deck before fitting though.

I suspect a 2.7m would be fine on the OPs narrower sterned 39 foot boat, but 3m probably too wide - will look odd and possibly get dragged when sailing?

 

[greeny]

Don't forget that two davits rated at 50kg each do not necessarily amount to 100kg capability. Allow for the heeling loads and shock loading in your estimates. For me, as a safety factor, I take the working load stated for one davit as the total load lifted by both. If you have them fabricated then this needs to be factored in the design calcs.
The other option is to use the hoop like davits that mount on the transom or bathing platform. I had these for a while but found them a bit fiddly and much prefer full davits.

 

[dunedin]

Don't forget that two davits rated at 50kg each do not necessarily amount to 100kg capability. Allow for the heeling loads and shock loading in your estimates. For me, as a safety factor, I take the working load stated for one davit as the total load lifted by both. If you have them fabricated then this needs to be factored in the design calcs.
The other option is to use the hoop like davits that mount on the transom or bathing platform. I had these for a while but found them a bit fiddly and much prefer full davits.

Agree. And in fact even when level, there may be 70% or more of the weight on the stern support, due to the weight of the heavy transom and outboard. We changed to a 3:1 with roller blocks for the stern, replacing the cheap plastimo 2:1 still retained st the bow.

The other key load factor is rain - or worse. Generally should leave the stern down slightly and the bung out, but inevitably sometime you will forget. And again the weigh is at the heavy end with stern panel and outboard motor. So need a substantial over spec for safety.

 

[ip485]

Davits - you will never look back, well only to check you have lifted the Rib onto the davits.