Transom mounted transducers - a venial sin?

[mtc]

Ok, i've done my homework on the cored boats and the disaster i recently saw when almost purchasing a balsa cored J 30 turned to oatmeal; i'm really wondering . . . -

can i mount my triducer for my raymarine 500x on my transom? It seems like the best place to get all three functions: depth, speed, temp - actually only place to get temp and speed.

if i use copious amounts of sealant, it shouldn't leak, besides, don't the four 1/4 20 rudder bolts go through the transom below waterline already?

if i'm going to freak out about the three #10 screw and seepage, then shouldn't i be a wreck over the seepage possibility from the rudders?

i need some saliant boaters' advice. please. someone slapped me. i had nightmeres about this and i'm out of prozac.

by the way, i absoultely love this little boat!!!!! it's the perfect combination.


michael

[Sloop John B]

Mike,

You don't need water temperature and speed thru the water. If you're thinking of taking a dip, stick your big toe in, or hold your mate by the ankles and give her a little dunk. You'll eventually get a GPS that will give you your speed over the ground. That's the only thing that's useful for what's happening.

For instance, I was sailing up the channel in Ochlockonee Bay on a beam reach heeled over 10 degrees leaving quite a wake. Then I get to watching this telephone pole with a green square on top urging me to stay to starboard, and it's practically going as fast as I am. Cutting quite a wake. Later study of a tide table with various intensities revealed I was sailing into a five knot ebb.

Your transom mount won't leak. I'd dab a little 5200 on the screw holes and then mount it. Others may recommend something a little less permanent for sealing.

Some guys have good luck with their transom mounts, others have them get busted off. In negotiating swells, they come out of the water and your screen goes blank.

For sounders, I think most puddy the transducer to the hull, away from the ballast tank and away from the turbulence caused by the centerboard trunk (or dagger board in your case). Under a dinette seat or under the rear berth.

[baldbaby2000]

Mike,
I'll be interested in how the speed transducer works. I'm thinking of adding one to mine. That in combination with the right wind indicator system will show you velocity made good (VMG) into the wind; a very useful number if you're trying to optimize upwind performance. A GPS can be used but if there are currents the system won't show correct VMG.

[flbum]

Is it still a sin if a dealer transom mounts a transducer for you when you didn't request the work???

I wanted to take the advice of other members on this board and mount the transducer for my Norcross depth sounder in plumber's putty. My Yamaha dealer had a little miscommunitcation with his technician and installed a transom mount transducer for me (and gave me the bill). My Yamaha dealer did a lot of extra unauthorized work. The technician told me that a transom mount transducer wouldn't have worked inside the hull anyway. It looks like there are several people on this board who would differ with that opinion.

So, I plan to mount the transducer for my Garmin 178C in plumber's putty inside the hull. I bought the shoot through the hull transducer, but I think that plumber's putty sounds easier to install and less messy than the mineral oil tank inside my bilge.

I think that I'll go with the "dip the toe" approach for water temperature. For speed, I'll go with the GPS which will be more useful for navigation than the "through the water" speed anyway.

The dealer did a pretty neat job of installing the transom mount transducer. He ran the cable for the transducer up above the waterline, then ran it through the hull using a clamshell to cover the hole. He sealed the screw mounting holes and the cable hole through the hull with LifeSeal. This is all probably standard operating procedure, but being a newbie, I was impressed.

I feel more uncomfortable about the unsealed gaping hole to the side of the transom for the steering rod than I do about the small well-sealed below the waterline screw holes for the transducer. But maybe that's cause this is all new to me.

Regards,
ROB

[mtc]

. . . and therein lies the dilema. . .

Having the temp isn't that important to me.

having the speed is very important to me (because i'm just a freak like that) besides, i looked at the gps color screens and they were out of my budget. granted, the raymarine 500 set me back $558. (at WM where their starting price was $669) but the gps I would want was over a grand.

Another point of the speed. It would be useful to see if my trimming had any impact on the forward motion of the boat. The GPS wouldn't necessarily do that because tidewater would be different than land speed. The boat would be going faster, hopefully, but if the tide/current changed, I wouldn't see the difference.

All these things are minor, childish 'wants' rather than needs. Lets fact it, all I really wanted was a dept finder - that's all, but with the prices up in the $300's it wasn't to much to get a picture of the bottom at the same time for a few dollars more.

Im ranting.

Anyway, Ill go with the transom mount but still need your guys' advice on where the best place would be to mount it - port/starboard and how far from the prop. Raymarine recommends at least 3" from the prop spin to prevent cavitation of the prop water, which would put it near the ladder. Port would put it near the valve.

I love these mini engineering projects.

Whats worth doing is worth doing once correctly.

Thanks for the help.

michael

[ronacarme]

Or see my 9/29/04 post re "mounted...depth transducer on...plate...clamped to transom".

[craiglaforce]

I originally mounted a depth/speed/temp transducer on my transom using epoxy. plenty strong enough withoug drilling holes. The speed thing never worked right and finally froze up or got some growth in the thing. I finally moved it inside and gooked it to the hull with some polysulfide caulk. still get good depth and temp readings. I would forget putting it on the transom. works as good or better shooting through the hull.

[Zoran]

Michael,
I've seen many transom mount transducers and nobody had a leak. Last year while sailing Glf Islands fellow Mac owner stopped and said Hey water is worm here lets swim and from our two boats 5 people were in the water in the meter of seconds. Nobody could get us out for an hour. Speed through the water is nice thing to know and helps in currents. I just purchased a new Eagle with speed and temp and my transducers will be transom mounted in next couple of weeks. What is the point of having all this options and not using them.
Zoran

[mtc]

i'm going forward with the transom mount making sure she's all sealed-up properly and throughly. as far as the paddle wheel jamming up, that's not cool. i did read that they don't last forever, so maybe that's what happened?

there should be a quick disco on the sounder so one could remove it easily when trailering. maybe i'll make one.

i'll try to locate that '04 string on transom mounted transducers although i don't find the search function that user friendly.

maybe it's me. . .

let you guys know.

[Duane Dunn, Allegro]

My transducer is transom mounted, I think it is a great option particularly if you want temp and speed so you can't do the shoot through method. There is really no reason to make a hole for a transducer in these boats.

The transom glass is quite thick. You can easily make deep enough pilot holes without penetrating all the way through. Goop up the screws and you will be fine. You can also locate the screws so they are in the ballast tank area, so a small leak really won't cause a big problem.

If you really don't want to make any holes, 5200 a piece of wood to the transom and then drill and mount in that.

For me temp is not something really useful, our water up here is either cold, or colder. But speed through water is extremely useful. The GPS speed over ground is rarely correct as it gets skewed by currents. Being able to see the difference between speed through water and speed over ground can help you make smart decisions as you now know what the current state is.

[Red Coat]

The boat I just bought has the depth finder attached to a piece of what appears to be white plastic "cutting board" that has been glued to the hull to avoid using screws into the hull. The transducer is then screwed into the cutting board. No holes, looks good and it serves the purpose well.

Larry

On another note "Zoran" I don't think the email feature on this discussion page is working right. I am interested in knowing if joining MYCBC is worthwhile.

[Zoran]

Larry
Please visit mycbc.ca you can e-mail comodore or vice comodore, and that will be me. If you still have problems my e-mail is [email protected]. Just delete delete.

[mtc]

duane, i like the idea of your mounting config - that's what i'll do.

thanks all you guys.

michael

[waternwaves]

Obviously Duane, you have sailed in some of my favorite unreliable wind and conflicing current spots around Orcas Island.....and Deception pass..

nothing like having a 10kt wind, a negative 1.5 kt ground track backwards.......lol.

Also Agree with Duane....in places with wildly varying currents....a paddle wheel water speed indicator is very Helpful.....maybe even a necessity.... especially in the fog.....or at night...... (I can't watch just the radar, GPS and immediately around me can I????)

[MMMike]

Where on the hull could you mount a transducer that misses the ballast tank?

I have a fish finder , with transom mount.
1. it gets covered with growth in days
2. speed wheel gets stuck
3. depth never works right

Looking at new instruments depth, wind gps

Any thoughts? Tictack wireless? Raymarine?
Will a Raymarine auto pilot work with different companies?

MMMike