Davit on bow- do I reinforce?

[stephen]

I am about to remove my swimplatform which currently houses my tender and place the tender on the bow.
looking for suggestions on best Davit to purchase for a 250lb tender and what I need to do to the bow, do I need to reinforce?
54c 2006

 

[REBrueckner]

Eerything depends on just where you'll be mounting the davit. I added one for the new owner of my 48 Hatt YF this summer and it took us the better part of a day to just measure 'exactly' heights and horizontal distances for proper placement of the 11 ft Boston Whaler. We got the height wrong by a few inches, due to the lift cabling inside the Whaler and he had to get an extension welded to the height of the davit. Everything else worked out well.

We utilized the base pipe about 30" or so thru the catwalk down to the level of the salon floor for fastening and support. Almost all the weight is carried on this pipe extension at this bottom, little weight on the deck or catwalk where all the forces are rather horizontal so the catwalk/deck does not carry much vertical force. [Someone who has successfully studied statics (like forces in trusses and levers) in undergraduate engineering courses should be able to visualize a reasonable solution...a current student could even figure out the forces for you....I did not bother as it was obvious to me what would work and what would not.

You need (a) sufficient arm height to get the dinghy where you want it on deck supports, (b) the proper distance from the side of the boat to enable you to lift the dinghy past the rub rail and (c) at a distance from the center of gravity at the cradle so you plan place the dinghy,(d) a way to support the thru deck pipe inside the boat. If you can't do all four, you might need to move up to an adjustable hydraulic arm and big bucks. Before drilling and placing, tie your crane/davit in place and view from dockside to see if it visually "fits" to your satisfaction. You also need to be able to get electric power or hydraulic lines through the interior mounting area.

In general, if the base is on deck near reinforcing like a bulkhead, rubrails or salon sidwalls, there is probably plenty of strength....just replacing, if you think it necessary,some deck coring with epoxy under the base should be enough. You can also use extra big washers under the deck, which we did, and perhaps an oversize aluminum plate, which we had little room for and so did not. My YF salon roof is not as solid as the catwalk where we mounted the lift so likely I would have wanted to use aluminum plate a backing on the roof. Mounting there would have given us the necessary vertical height but the davit looked out of place when viewed from dockside.

Look at some neighbors installations in similar positions to ones you might consider before starting and before purchase. I located a used lift here on SAMS...came off a 53 Hatt I think.

 

[MikeP]

Seems like you would need the davit to go through the deck and mount to some substantial portion of the boat's structure - like the davits that are mounted on the flybridge. The normal setup is that the pipe that holds the davit goes through the FB deck and then bolts to the main deck. So the leverage provided by the length of the pipe and the fact that it's bolted to the main deck makes it capable of safely lifting a good load without fear of it pulling loose because the main load on the post is sideways which is in the strongest direction of the deck and the fasteners.

Mounting it forward means you will not have that mechanical advantage that the long lever provides and just bolting it to the deck would, it seems to me, almost guarantee it would rip loose under load though if you had a large and thick enough backing plate under the deck, it would be OK. But how large and how thick? I'd sure contact someone who makes or installs them professionally to see what they recommend.

 

[Brian Degulis]

Just look at similiar boats. Most of the Cs that I've seen the vertical pipe going thru the deck in a closet or alongside a bulkhead and it's tied into the floor. The more space there is between the upper deck and lower deck the less strain on both decks. The less height there is above the upper deck the less strain on the whole structure. There's no way your going to be able to it without going thru the deck. I would also make something with at least a 700 lb capacity for resale purposes.

Brian

 

[stephen]

thanks for your response, this is all very useful

 

[GJH]

The first thing you should do is call Hatteras. This is a newer boat and they mounted davits as an option and should be able to tell you exactly what to do. If not, call Jarrett Bay as they did a lot of the commissioning of these boats.

 

[worldsaway]

You have to have a stand pipe that runs through the deck and usually attaches to a floor or stringer inside the boat. My friend 2005 54c has the stand pipe in the owners stateroom near the entrance to the head. It is out of the way. He has a Marquipt hydraulic davit but he has a 13ft whaler he lifts at 1000lbs. Marqupt makes a nice 600lb and 800lb davit. They are pricey but there are usually used ones out there in good shape.

 

[kwerges]

On my 42C, the standpipe runs through the deck, through the master stateroom closet floor, and attaches to the stringer underneath. I have a 600lb davit to lift an 11' Whaler, and that is about the limit of a single pull lift on the Whaler. I also had a "strongback" made for my Whaler so I could lift it over the bow rail...

 

[REBrueckner]

I assume you have reasons for removing the swim platform. Keep in mind they are a great safety device in a man overboard situation and removing it may make it difficult to get anyone out of the water....

 

[TopHattandTails]

maybe you could install some single steps/ foot holds to the transom to get out of the water and into the rear door...