Electric Trailer Winch Mast Raising

[TonyMills]

I am using a small electric trailer winch on a temporary fordeck base to raise the mast after I go under bridges in Fremantle. The winch is new and theoritically has a single line pull rate of 900 kilos. It is wired through to the battery using crocodile clips and this wire is about 6metres long. and I run the engine during operation.

I find that the pull rate is much slower than expected and I usualy give up and pull it up with a three sheeve block and tackle which is attached just in case.

Could this be because of the length of the wiring between the winch and the battery? Or is the idea not viable because cheap trailer winches are not strong enough for the levered weight when raising a mast fitted with a spinnaker pole 'A' frame on a 30ft boat?

 

[William_H]

The thing about mast raising is that you have a really heavy load when the mast is down which gets smaller as the mast comes near vertical.
So if the winch is going slow and well loaded when the mast is down it will not necessarily spped up as load reduces near vertical.
Might I suggest the winch be paralelled with a 4 part purchase that you bring into pl;ay as the mast gets closer to vertical which you pull by hand. Certainly you want it up and stable as soon as posssible. good luck ....olewill (EFYC)

 

[oldharry]

There is no way you are going to acheive a 900kg pull yourself, even with a 3:1 tackle! To acheive a 900kg static pull cheaply the winch will be using a small highly geared motor - cheap but very, very slooooow! IOW its the winch that is rubbish, not your wiring. Either live with it, or get a 'proper' winch.

When I had a trailer sailer, I rigged the trailer winch to raise the mast single handed. Efficient and very effective.

 

[graham]

your bath water may go down the plug hole the wrong way but it sounds as if your masts behave the same as ours. /forums/images/graemlins/cool.gif

i pull the mast up on my 22 footer using a pole on the front and a rope through a block on the foredeck led back to a sheet winch.Until its nearly halfway up the strain on the rope is enormous,both hands needed on the winch.After that its easy . I am reluctant to use a block and tackle in the system as it would slow the operation down.

 

[rogerthebodger]

The pull (force) needed to rase a mast can very easily be calculated by using a vector force diagram.

The info needed is
1) the weight of the mast at eash end when lying down.

2) the length of the mast

3) length from pivot to pulling rope attachment if not at top of mast

4) length of spinnaker pole 'A' frame

As others have said most load will be when mast is lying down horizontal, reducing at it rised.

If the speed of your electric winch increases as the mast is lifted, the winch could be load sensitive if not I think its just a slow winch. The cable length could increase the resistance causing a volt drop but I think the wire would get warn if that is the case.

Have a look at the power / current / Amp rating of the winch then check the wire size for the current rating of the winch.

I am building a removable mast pivot / A frame for my 15 m mast on my new yacht and plan to use my 1200 Watt windlass to raise the mast using a 6 m A frome. My mast is about 185 Kgs so needs some strong equipment.

 

[VicS]

I'm not going to get into calculating the pull required to raise the mast from the horizontal position. Roger Shaw has taken the lead role there.

However if you have any doubts about the electrical installation voltage losses why not monitor the volts at the winch Then you will see if there is excessive volts loss. Even if the cable used is adequate you could still be dropping volts through poor conections etc.

 

[TheBoatman]

Crocodile clips on the battery to run an electric winch /forums/images/graemlins/tongue.gif

Peter.

 

[TonyMills]

Thanks, more testing

 

[TonyMills]

Thanks, I'll do the sums. My mast is a fairly strong section about 10.5 metres.

I can raise it using the three part block and tackle but its hard work hence looking for alternatives.

Regards
TonyM

 

[TonyMills]

Thanks

knowing the location you will know the problem. Its the time taken to get it back up before the next motor yacht ploughs past. I have a block and tackle which I can use alongside so I'll try that. The only problem then is adding to the overall rigmaroll of lowering and raising the mast, which is already complicated enough.

Then again why else do we have boats

Regards
TonyM (RPYC Crawley)