Best way to fit a depth sounder?

[Andy Best-Dunkley]

Hi everyone! What have you found is the best way to fit a depth sounder to a Wharram hull? I've got a Nasa unit that I'd like to fit. Options seem to be:

- shape a suitable "pod" to fit to outside of hull, and lead sounder unit through hole into hull.

- remove plywood from suitable area of the hull, and fill with expoxy/glass laminate, then fit sounder inside hull in oil bath (as can be done with glassfibre boats)

- use some lifting pole system suspened between the hulls from the crossbeams that can be raised and lowered.

Each solution seems to have some advantages and disadvantages - what has worked best for you, or is there some other ideal solution I've not thought of!

Thanks for ideas!

Andy

[Robert Sheridan]

On my Hinemoa the thickness of wood in the keel meant that I could drill through and fit the transponder so that it was flush with the bottom of the boat.  On the Tiki 30 we have now there is a blister/pod on the bottom of the keel which allows the transponder to be fitted in the same way, there is not enough width of wood in the bottom to do otherwise.

I did experiment briefly with a lifting pole but there is a lot of drag when it enters the water and you have to remember to deploy it.  The only other alternatives I have come across are the hand held electronic depth sounders, a friend used on his Tiki 21 by reaching over the side, and I have seen transom mounted transponders on power boats which seem to be an external fitting but know nothing more about them.

Robert

[Ann and Neville Clement]

At least fit it to the starboard hull so you measure the depth of water at the edge of the channel when entering port through a narrow channel. 

[Andy Best-Dunkley]

Thanks for your comments so far! I'm reluctant to have extra holes through the hull if possible, so my preference is to go with the internal hull fitting, with transponder in oil bath epoxied to inside of hull. But I'm wondering if the extreme V shape of Wharram hulls will distort the signal too much, even if I make that area of the hull with glass/epoxy laminate with plywood removed? Has anyone tried this?

Thanks again, Andy

[SoLong]

Hi Robert,

where is your blister/pod located under the Tiki 30? Did you drill a hole throug the keel? I use the tacktick system. Their dephtsonders have a diameter of 5cm. So I'm very afraid to loose the stability of the keel, if I drill a hole through.

Do you have any photo?

Thanks!

Gerhard from Solong

Robert Sheridan said:

On my Hinemoa the thickness of wood in the keel meant that I could drill through and fit the transponder so that it was flush with the bottom of the boat.  On the Tiki 30 we have now there is a blister/pod on the bottom of the keel which allows the transponder to be fitted in the same way, there is not enough width of wood in the bottom to do otherwise.

I did experiment briefly with a lifting pole but there is a lot of drag when it enters the water and you have to remember to deploy it.  The only other alternatives I have come across are the hand held electronic depth sounders, a friend used on his Tiki 21 by reaching over the side, and I have seen transom mounted transponders on power boats which seem to be an external fitting but know nothing more about them.

Robert

[Alf Bangert]

Hi Andy,

I think you are right that the angle of Wharram hulls will distort the signal with an internal installation.  I once had that setup on a Marieholm Folkboat,  and it worked,  but not well.  The hull angle in that case was about 45 degrees and the transducer was immersed in castor oil in a tube epoxied to the hull.  Obviously in a Wharram the hull angle would be much steeper with significant signal loss.  Based on that experience,  I decided to make an external fairing (blister to some) so the transducer face on my Tiki 38 could be in the water and vertical.  The fairing cavity is bulkheaded off inside so that even if the transducer fitting failed completely,  it would only flood about 1 gallon of water.  The area is accessible from inside through a screw in port fitting.   This neatly solves the problem of a big hole in the hull.  It was a bit of work alright,  but this was too important to cut corners on.  Your depth sounder is your eye to the bottom,  and in my opinion the most important electronic instrument on your boat. 

-Alf

Andy Best-Dunkley said:

Thanks for your comments so far! I'm reluctant to have extra holes through the hull if possible, so my preference is to go with the internal hull fitting, with transponder in oil bath epoxied to inside of hull. But I'm wondering if the extreme V shape of Wharram hulls will distort the signal too much, even if I make that area of the hull with glass/epoxy laminate with plywood removed? Has anyone tried this?

Thanks again, Andy

[Andy Best-Dunkley]

Hi Alf,

Thanks for your comments and picture - very streamlined pod you have made! Yes, I think you are right about the distortion if the transponder unit is inside the hull, this is what I suspected. A very good idea to build additional bulkheads inside in case of leaks.

Thanks, Andy

[boatsmith]

This is a nodule we made of glass and installed for the transducer. I too tried a hinged leg on another boat and did not dig it.

[Klaus Pedersen]

Fitting the transducer inside the hull will reduce the signal strength and thus the efficiency of your sounder no matter how you do it. I have tried mounting transducers on various contraptions, sticks etc., on different boats, it works, but as a permanent solution it's a bit annoying: deploying, routing cables and so on.

I'm in the process of building a T38 and will soon fit a pod with an internal box and a watertight inspection hatch on the inside, more or less as Alf Bangert is describing - on the stb hull. This seems to be the way to go on Tikis.

Cheers Klaus

[Robert Sheridan]

Approximately under the forward beam on the starboard side, back from the forward bulkhead.  You would not want it any further forward  because of hobby horsing.

SoLong said:

Hi Robert,

where is your blister/pod located under the Tiki 30? Did you drill a hole throug the keel? I use the tacktick system. Their dephtsonders have a diameter of 5cm. So I'm very afraid to loose the stability of the keel, if I drill a hole through.

Do you have any photo?

Thanks!

Gerhard from Solong

Robert Sheridan said:

On my Hinemoa the thickness of wood in the keel meant that I could drill through and fit the transponder so that it was flush with the bottom of the boat.  On the Tiki 30 we have now there is a blister/pod on the bottom of the keel which allows the transponder to be fitted in the same way, there is not enough width of wood in the bottom to do otherwise.

I did experiment briefly with a lifting pole but there is a lot of drag when it enters the water and you have to remember to deploy it.  The only other alternatives I have come across are the hand held electronic depth sounders, a friend used on his Tiki 21 by reaching over the side, and I have seen transom mounted transponders on power boats which seem to be an external fitting but know nothing more about them.

Robert