Is Compass Compensator Necessary?

[jh2005]

Hi,

We are thinking of replacing the compass on our Westerly Pageant. The old compass is a traditional gimballed one fitted to a removable bracket low down on the port bulkhead, but would like to replace it with a newer model. A look around the boatyard & chaldlery reveals the bulkhead mounted Plastimo Contest 101 to be fairly standard equipment. Before parting with the cash I have a couple of questions you may all be able to help me with:
1) Is the optional compensator necessary on a 23' GRP yacht? (Engine is 1GM10 about a metre below where we would install compass)
2) Would our seafarer 'whirlygig' depth sounder's electic motor affect the compass - about 15cm away?

Cheers,

James

 

[snowleopard]

compensators are rarely needed on grp boats, they are mainly for steel.

an electric motor 6" away may cause a problem. try standing a hand-bearing compass at that distance and seeing if it moves when the sounder is switched on/off.

 

[srm]

Fit the compass and check for deviation, you can presumably buy the compensator later but will probably not need it. If the engine is directly below the compass you may get heeling error which the standard compensator is unlikely to compensate.

Follow the suggestion for using a handbearing compass in the position first, but as the echosounder uses an electric motor I would expect deviation at that range with it running and possibly with it off.

Other likely sources of deviation include VHF radio and anything ferous or electronic mounted on the inside of the bulkhead.

There was a string about checking for deviation a while back.

Sean

 

[jh2005]

Thanks,

We fitted the new compass last weekend on the bulkhead the opposite side of the companion-way to the echosounder, just need to get the boat back in the water for a full test now!

James