placement of hoist

[jacothebrave]

Help the not so smart please

With a pontoon boat
Pontoons 660 mm
Center of pontoon to center of pontoon 2.1 meter
To build a hoist lift or whatever you call it
Vertical Pole 2 meters high
Horizontal pole 500 mm over pontoon
1st case vertical pole in center of boat horizontal pole 1.88 meters
2nd case vertical pole 400 mm inside center of pontoon horizontal pole 1.23 meters
Which is the better one to lift something out of water or are it basicly the same


All assistance will be apreciated

Regards
Jaco(the not so smart LOL)

[CDK]

Moving the vertical pole away from the center of the boat saves material because the horizontal one can be shorter. For the stability or lifting capacity it makes no difference whatsoever where you mount the hoist, that is solely determined by the buoyancy of the pontoon that is being pulled down and the weight of the one lifted.
A movable counterweight can yield extra lifting capacity.

[LouisHeyman]

Hi I am the reason for Jaco's Question.

What should be noted is:
The boat is a 7.5m long 540Kg aluminium pontoon boat.The weight includes the engines and roof. The max weight that might be lifted is 200kg. The boat will be operated in a harbour.

I said the main pole of the hoist should at least be in the centre and that putting the hoist over the pontoon will cause the boat to become unstable and it stands a good chance of lifting the other pontoon out of the water, more so when the hoist is fitted to the pole of the roof over the boat, because the roof is fixed right above the pontoons on both sides.

Do you still think it does not make a difference?

[LouisHeyman]

Forgot to mention. The hoist arm actually extends to about 1/2 meter outside the boat

[CDK]

The only factor determining the stability is the width of the boat and the reach of the arm that extends from it. Instead of a construction of poles, think of a vertical plane of a piece of plywood as wide as the boat is and extending 1/2 meter over the side, where it is loaded with 200 kg.
No I guess you'll understand.
It does not matter where you fix it to the boat, the arm x load is all that matters.