Davits on a Fairline Corniche, how much weight ?

[Fusebox]

Hello everyone.

I have a Zodiac YL310 (54 kg) with a small Tohatsu 2,5 hp outboard on our davits, without any problems. Total weight is about 65 kg.

How much can the mounts on the transom take, without using any special brackets ? I am not concerned with the davits, as they are strong enough.

I'm thinking of adding another 8 kg. by swapping the 2,5 hp outboard for a Mercury 5 hp (20 kg), making the total weight about 75 kg.

Any suggestions ?

Thanks.

 

[volvopaul]

Firstly what make of davits , I had a corniche some years back it had whit tall ed 17s bolted straight on the horizontal pad area and took an Avon 280 rib and a mariner 4 no problem.

 

[Fusebox]

The make is ILAS Marine, a norwegian company. Not sure of the model, but I believe they are rated well above 50 kg. each.
I have not measured the distance from the pad to the lifting point, but i reckon it is about 65 cm.

The foot of the davit is a bit bigger than the Corniche pad, so it goes out about 3 cm. beyond the pad. The point of weight (or CG) might be a bit affected by this, but I do not think it makes much difference.

The Avon 280 is about 61 kg. ? And the 4 hp. engine probably similar to a 5 hp. at 20 kg.

Thanks volvopaul. Always good to have a practical reference

I do see the transom flex a little when I push on the davits, with the boat loaded, but does not seem to be struggling with the weight.

Think I'll stick with the 2.5 hp. engine for summer holiday. With the current wind around here, we are likely to see frequent waves between 5-8 feet, so best not to push my luck.

 

[Divemaster1]

ILAS Davits I beieve starts at 75Kg load each.... and goes up to 150Kg (at least did last time I looked).

Remember that it is usual to calculate davit load so that each of the davits can carry 100% of the weight. simple reason for this is the snap load that is generated when boat moves in waves and dinghy (which may have water in it) move out of sync with the mother vesel. (Although ILAS does have the ability to lock the dinghy quite hard up against the davit itself). My main concern would be the load on the davit fasteners (bolts & nuts) on deck/hull and the strenghteners behind this... such as a SS plate to spread the load.

We used to have a Zodiac 320 on Simpson Davits behind an Apollo 32, but never carried the outboard in it. Mostly because she threw up an lot of water which landed in the dinghy. Friends had a Fairline Phantom 32 with the bigger Simpsons... and they carried a With 320 with a 28Hp Mariner in the davits most of the time. Only time engine came off was when crossing the open stretches of Stadt, Jæren, Lista & Lindesnes... However, both of us carried significant and braced SS strenghteners of stern and deck...