RL24, RL28, and RL34 Trailable Yachts
from Rob Legg Yachts

RL Yacht Owner's Discussion Forum

Return to the Forum List

Humminbird TCR ID-1 Transducer
The fishfinder sensor/transducer of my recently purchased RL24 has had its pivot eyes broken off and there is no bracket for transom/hull attachment. The sensor is located in the stern, adjacent to the outboard well, and just flops around unattached - quite useless at present however the sensor still works.

I've also discovered a second sensor in the bow area underneath the toilet. It was simply attached by a bracket to a wooden support with the sensor sitting on the bare fibreglass hull.

Garry (02/12/2001) used silicon to fix his transducer to the hull. This has the advantage of being able to move the sensor to a better area if necessary. This seems to be the solution for my stern sensor. However the Humminbird manual recommends using epoxy (permanent) and cautions against using silicon or soft adhesives as they will reduce sensitivity.

Keith Merkley (12/08/2001)recommended inserting the sensor into PVC pipe, gluing it to the hull, filling it with caster oil and capping the pipe. This would seem to be the solution for my bow sensor. But why caster oil ($50 per litre)? Why not water (free) or vegetable oil (a couple of dollars)?

Could Keith or Garry or anyone else comment further on the use of silicon and sensitivity and the reason caster oil is used rather than other fluids?

Best wishes,

Terry Stannus,

RL 24 No 64 'Good Feelings'

Terry Stannus26-Apr-2003    Edit    Delete 
transducer mounting
Hi Terry, Mounted my Eagle fishfinder transducer to the hull using waterproof Silastic. Mounted in area just below cockpit aft of companionway. Just built up a pad about 5mm thick, running adjacent strands, then wiggled the transducer in. Be careful not to enclose air bubbles. No problem with sensitivity, still sensitive to pick up jelly blubbers in water, and differentiate between weed, mud or sandy bottom. My manual also recommends epoxy, but after doing it with silastic, would never go that way. Much too permanent! rgds, iggy

ian green27-Apr-2003    Edit    Delete 
Transducer mounting
Dear Iggy, Thanks for the prompt reply. You have had success with Sikaflex so I'll go the same way.

It seems that you have mounted your transducer inside the hull with Sikaflex and fibreglass between the transducer eye and the water. I'll mount my bow transducer as you have, inside the hull with Sikaflex.

With my stern transducer I have the option of mounting it inside or outside the hull. If outside, adjacent to the outboard well, I would have the benefit of best sensitivity as the transducer's eye would make direct contact with the water with the Sikaflex securing the upper side of the transducer case to the hull.

If mounted inside there would be the added benefit of protection of the transducer from collision. If sensitivity is not an issue then this should be the way to go. As you say it is not permanent like epoxy so I can experiment.

Thanks again Iggy, With best wishes, Terry

Terry Stannus28-Apr-2003    Edit    Delete 
transducder mounting
Terry, Please note I used marine SILASTIC, not SIKAFLEX. From what I hear this stuff makes an awfull mess. rgds, iggy

ian green28-Apr-2003    Edit    Delete 
Humminbird are against the use of silicone (silastic) because it may reduce the sensitivity of the unit and if air bubbles are present it will do more than that.

But. Humminbird are in the fish detecting game, we just need to know where the bottom is, so silicone may be OK.

If you stick it down with silicone and it doesn't work it is no great loss as silicone is next best thing to useless as an adhesive. And as a sealant.

Sikaflex sticks like shit to a blanket and if you use it you might not be able to unstick it without damaging the transducer. It's only as messy as the operator.

For just about all marine sealing, I use Bostik seal'n flex. It leaves silicone for dead and can be removed (with difficulty) and is much cheaper than Sikaflex. To test for a suitable location, sit the transducer on a plastic bag filled with water. If there are no air bubbles, it should shoot through the hull as water and fibreglass have a similar ability to conduct sound waves. I tested the hull of my Mk 3 and couldn't get the tranducer to fire through it where I wanted it to, so my transducer is mounted in the outboard well just ahead of where the outboard used to be. It is actually through a hole in the glass and stuck in place(and waterproofed) with seal'n flex.



mike28-Apr-2003    Edit    Delete 
In hull mounting of transducer
Please see the Tips page on this site for a diagram of in hull mounting of the transducer.
Keith Merkley17-May-2003    Edit    Delete 

Return to the Forum List       Add a message to this discussion