Transducer position MF 655 and Marine loo.

[mattcrisp]

Please does anyone have any experience of fitting a through hull transducer or an in hull bonded transducer to a 655. There appears to be an area of single skin hull just by the battery switches. Is this designed for transducers? 

Any info about sea cock position appreciated for a marine toilet. Also any fitting advice.

Matt

[bombastique]

Yes the single thickness skin below and slightly aft of the switches is where my transducer is fitted on the port side. In that position it works very well at all speeds on my 655.
The sea cocks for a sea loo are forward of the loo in the same compartment. Make sure you fit the intake forward of the outlet. I understand if the boat is being used on fresh water or in some places abroad you will have to fit a holding tank.

[mattcrisp]

Thanks for that. Is yours an in hull transducer or a through hull one. Matt

[bombastique]

Hi Matt,

Mine is a thru hull transducer with a Navman digital sounder. It is more of a job to put in a thru hull transducer because the boat has to come out of the water. However the performance of a transducer in an oil bath inside the hull can be variable for the following reasons.

1. The transducer is sounding through a thickness of glass fibre which may have tiny air bubbles just where the transducer is sounding through. This reduces the sensitivity and almost certainly the ultimate performance.
2. The antifouling in that area has to be reasonally thin and again no air bubbles in it.
3. The tube in which the transducer is fitted has to have the oil in contact with it at all times so no oil leaks are permissable.
4. The angle of the beam of the transducer is affected by the passage through the oil and the hull so that although it does not affect you, the transducer can end up looking at the keel on a sail boat because the beam is so much wider.

Sorry to drag on but I worked 25 years (now retired) for an instrument manufacturer and the best all round solution is to have a unit that can be withdrawn for cleaning whilst the boat is afloat. Unfortunately it is a bit expensive for our type of boat and not really necessary. I'm sure many users get away with the oil bath solution but I prefer to drill a hole in the hull and bolt it through.

Don

[mattcrisp]

Hi Don
Thanks for the info. Been wading through the current available echo sounders/fish finders. Chirp seems to give good detail but not at depth. I cant find any review that will advise on best for stand alone finder with a big screen on normal frequency plus chirp with a through hull transducer. Im not keen on removable ones after being soaked many times cleaning paddle wheels on yacht speedos. They also seem to want megabucks for the kit. Fitting is easy as she is on a trailer in the barn at the moment.
Do you have any suggestions for finders. I have a big Garmin chart plotter, but the finder module and transducer to fit are £1500.00

Back to heads. What make of loo do you have? Jabsco seem to be the best. Have you got anti siphon loops? I guess I will have to cut the inner skin out to a size to accommodate the nuts and a spanner on the fittings, and cut clearance holes for the sea cocks through the main hull?

Have you fitted two batteries? I still have just one with the Jenneau pos neg on off switches. On last boat one battery was dedicated engine start, the other was house/instruments. I think the Yanmar alternator will charge both easily. 

Regards Matt