Transom mount sounder height.

9D280 · 05 October 2012, 16:04

OK, I know the water tends to rise after the transom passes.

Lowrance tell me to mount the sounder wit hthe centreline level with the bottom of the boat. Belagio would be calling me for advice on their next display if I left it there.

I raise it 1/2" so the botom of the sounder is now level with the boat, and I still have an A- frame + antenna high fountain.

As this could go on a while, could anyone whose transom is accessible give me a couple of measurements -
1) height of bottom of sounder unit wrt bottom of boat
2) distance form transom to leading edge of sounder.

I just want to get a feel for how much further up I need to move it. Unless they all produce jetski style tails?

Markyboyo · 05 October 2012, 16:50

Always had this problem myself despite experimenting with different heights and angles. In the end I just went with the position that gave the sounder best performance. I've just had a shroud made up to fit on the transom above the transducer to stop the side of my engine cowel getting sprayed all the time.

ncp · 05 October 2012, 20:35

I'm not pushing their system, nor did I buy one for myself, but I found it and interesting read:
http://www.sternmate.com/Where.html

Pikey Dave · 06 October 2012, 08:58

Quote:

Originally Posted by 9D280

OK, I know the water tends to rise after the transom passes.

Lowrance tell me to mount the sounder wit hthe centreline level with the bottom of the boat. Belagio would be calling me for advice on their next display if I left it there.

I raise it 1/2" so the botom of the sounder is now level with the boat, and I still have an A- frame + antenna high fountain.

As this could go on a while, could anyone whose transom is accessible give me a couple of measurements -
1) height of bottom of sounder unit wrt bottom of boat
2) distance form transom to leading edge of sounder.

I just want to get a feel for how much further up I need to move it. Unless they all produce jetski style tails?

A bit off piste, but have you considered bonding the transducer to the inside of the hull? IMHO & experience, you get far better results at higher speeds if it's done correctly & you can find a good mounting spot.

ncp · 06 October 2012, 13:38

Quote:

Originally Posted by Pikey Dave

A bit off piste, but have you considered bonding the transducer to the inside of the hull? IMHO & experience, you get far better results at higher speeds if it's done correctly & you can find a good mounting spot.

Airmar P79 is less than $100 or building your own reservoir and bonding the skimmer transducer is pretty easy too.

jyasaki · 06 October 2012, 15:41

I'm running a skimmer ducer on my al hull. The hull at the back of the motor pod (the bottom of the pod is an extension of the hull material, so at the same level) has a 1.5" lip. The ducer is mounted to a block of plastic that is screwed and glued with the screws coming up through the lip (to avoid holes to the inside of the boat.)

The ducer sits about even with the bottom of the hull; a line extended from the bottom of the hull running surface hits the ducer pod just about at the widest part of the oval cross section. As far as setback, I'm using the factory bracket, and it is mounted even with the rear of the bottom lip (I suspect this doesn't have a whole lot to do with your problem.) I found that running the trailing edge of the ducer a click down from flat works best for me.

The white stuff in the pic is a slathering of epoxy covering some SS wire reinforcement, made necessary after hitting a piece of lumber on a return from a fireworks show in SF Bay one night. Snapped the ducer at the marrow part of the arm.

jky

9D280 · 08 October 2012, 17:26

Thanks for the replies-

Quote:

Originally Posted by Pikey Dave

A bit off piste, but have you considered bonding the transducer to the inside of the hull?

Would do, but as my hull is of 1980s vinatage, (no drain well) the only place I can get a "clear shot" through the fibreglass etc (i.e clear of the void) is so far off centreline that it isn't in the water when on the plane!

Jyaski,
I had thought of 'glassing a surface off the transom so it was better protected, but thought I would try a "standard" fit first. I had noticed two "dropouts" at speed on the test run, so may need todrop it back in a bit

Marky,
That idea is on my "if all else fails" list

Pikey Dave · 08 October 2012, 20:55

Quote:

Originally Posted by 9D280

Thanks for the replies-

Would do, but as my hull is of 1980s vinatage, (no drain well) the only place I can get a "clear shot" through the fibreglass etc (i.e clear of the void) is so far off centreline that it isn't in the water when on the plane!

My transducer is under the deck bonded directly to the hull. I had a Bailey Hatch put in the deck to give me access. I know I'm banging on about it, but it really was a revelation to me having a "thru hull" It solves so many problems.

gotchiguy · 08 October 2012, 21:07

Quote:

Originally Posted by Pikey Dave

I know I'm banging on about it, but it really was a revelation to me having a "thru hull" It solves so many problems.

From your posts above don't you mean an "in hull"?

Although a "thru hull" could be a good option...talking of which...I have a lovely Airmar P19 thru-hull sat here which could be yours for not very much..

Seriously..

jyasaki · 08 October 2012, 21:07

Quote:

Originally Posted by Pikey Dave

I know I'm banging on about it, but it really was a revelation to me having a "thru hull" It solves so many problems.

Depends on the boat you have.

9D has an inboard, so most likely the rear centerline out to close to the chines is inaccessible. Further out will either lift out of the water at speed, or be heavily shadowed by the deadrise.

In my case, I've got a 1/4 of aluminum between the bilge and the water; there are transducers that will shoot through (I think), but they're way expensive. Hence, the transom mount.

jky

Pikey Dave · 08 October 2012, 21:20

Quote:

Originally Posted by jyasaki

Depends on the boat you have.

9D has an inboard,

I thought he had a 60 Clamshell.

Gotchi, you're right (make the best of it

) I meant "in hull"

jyasaki · 09 October 2012, 20:18

Sorry, Dave; I think I'm getting posts mixed up between 9D280 and NCP, both of whom are trying to mount ducers.

jky

Pikey Dave · 09 October 2012, 21:21

Quote:

Originally Posted by jyasaki

Sorry, Dave; I think I'm getting posts mixed up between 9D280 and NCP, both of whom are trying to mount ducers.

jky

no worries

9D280 · 10 October 2012, 09:43

5M rib with an Inboard..... I'll make that my next project!

I have toyed with the hatch idea, but having owned a "floppy floor" searider and as this one is solid, I don't really want to be cutting holes if I can avoid it.

BogMonster · 11 October 2012, 09:25

Quote:

Originally Posted by ncp

Airmar P79 is less than $100 or building your own reservoir and bonding the skimmer transducer is pretty easy too.

Not building your own reservoir and just dumping a big gloop of silicone into the desired place and working the transducer into it to avoid air bubbles worked for me - all of 5 min

My old Humber transducer mount was a pain and I broke it a couple of times in kelp and regularly had to reset it. In-hull is fit and forget...