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Discussion Starter #1
I'm looking for an inexpensive route to get speed and depth data in the cockpit of my C&C 25. I don't plan on any other fancy instruments just the depth/speed mounted on the port cockpit bulkhead. I also don't plan on doing much more than day sails or an occasional overnight.

I was ready to pull the trigger on the Raymarine ST40 Bidata but from all the installation instructions I downloaded it requires two through-hulls. My boat currently has a through-hull installed for the old knot-meter which I would replace with the new paddle wheel, but I really don't want to drill another hole in the hull if I don't have to. From looking over thier product website, Raymarine does not sell a combo transducer (speed/depth) for the ST40 series instruments.

What other options might I have that is economical and requires only one hole?
 

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I have owned 5 sailboats between 14 and 24 feet with up to 4' draft and never had a depth finder and race on a 7' draft boat without one ;)

I do have one on my 19' powerboat and it has allways been to little to late with the chartploter being the item that been far more usefull IMHP :)
 

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I'm planning on installed an ST40 and using the thru-hull transducer as an in-hull. You can search "shoot through the hull" for more info. I'd be surprised if it doesn't work. If I do run into issues, I will contact Raymarine and find out why the Airmar P79 wouldn't work for the ST40. They list the same transom transducer for the ST70/60 and the ST40 so I believe that the in-hull should work.
 

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Don:

You should be getting some really good input from the knowledgeable folks here in a very short time.

In the interim, we have the ST40 and have been relatively satisfied with it.

Since you only want depth and speed (presuming through the water only), do you need Bidata? I'm under the impression that's only required if you want to combine with wind speed/direction. I'm sure someone will correct me if I'm wrong.

Also, I thought the ST40 was at or near the end of its life span. If I'm correct, that could make servicing difficult in the future.

Have fun!!!
Paul
 

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Don—

You can use the knot meter in the old through-hull and you can probably set the depth transducer to shoot through the hull, provided your boat doesn't have a cored hull.
 

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some of the black and white combo fish finder / gps only run around 300. if you hull is solid you can get away with making it a shoot thru.

its what i plan on for me
 

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Discussion Starter #8
Its a solid hull, cored deck.
I have read here at other times how to do this in-hull 'ducer, but I will have to go back and re-read the how to's on it.

Still up in the air what to do, and I'm really wanting to get this taken care of before the boat goes back in the water in a couple weeks.

Thanks again
 

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here is a hummingbird 363 for 300 bucks. it will give you water depth, speed over ground, anchor alarm IIRC, a look at the bottom, and basic chart functions. it is black and white with a 4 inch screen, while not huge it will do what you are looking for. as for the transducer you should be able to either use epoxy or a wax toliet ring to "glue" it down some where in the hull that works

after i get an auto pilot it is what i plan on getting
 

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You can use GPS for speed - it is a lot more reliable than those little silly paddle wheels that get fouled up as soon as they hit water. That and a really old depth sounder - that's all the instruments I have. Don't really need others. Wind would be nice to play with but I hardly miss it.

Total cost of a little GPS - $50 used.
 

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If it was a through hull 'ducer I'd buy it, however its transom mounted and probably not the best placement for keel boats
Oh there are several listed, and I did see one with the through hull "triducer." The triducer gives you speed, temp and depth. If you don't use the triducer, you'll need two transducers, a log (speed and temp) and a depth.

Do a search for "Comnav" there are several well priced options available.
 

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It's not best.

If it was a through hull 'ducer I'd buy it, however its transom mounted and probably not the best placement for keel boats
I have used them. I had a Stiletto Catamaran, very light, and was not about to drill a hole. The hull is cored. The transom mount units work, with some notes:

* placement and angle is critical. Someplace where the flow is smooth.
* expect problems in chop and at speed. Mine would not work past about 9 knots (!). Actually, any time air is getting under the hull.

Of course, at slow speeds they work well, and that is when it was most usfull - anchoring.

It was a fair choice for that boat, but I wouldn't use it on yours, I think.
 

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Value of speed meter

While it is true that GPS will give you more accurate Velocity over Ground, sometimes you want to know what the speed over water is. Depends on your use of the boat, preferences, and willingness to spend the money.

The speed over water gives you a better feel for how you are sailing the boat, as opposed to how much distance you are making. You can really focus on changes to speed even if you are fighting a current.

Just a matter of preferences.
 

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I use my GPS for speed and a cheap fish finder (Eagle)for depth. It's also good to tell me what the bottom is like when I want to anchor. I think that I paid around $85 for the depth finder. I siliconed the transducer right to the hull no problems in three years. Did the same on my last boat.
As for the speed, my hand held GPS is accurate and has a large readout. I paid less than $100 for the GPS on ebay, so for under $200, I'm set.
 

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Discussion Starter #17
Just curious, those of you using fish finders on tiller steering boats (20-30'), where are you mounting the fish finder display?
 

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Discussion Starter #18
I had another development while snooping around for a place to locate a transducer and found that my boat already has a thru-hull transducer and fairing mounted. All I will have to do is find another display that will work with it. This makes half the job a price easier to deal with.
 

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mounting

On my second boat, I mounted it on a board that flipped out into the companionway when I was sailing. It folded back in when I needed to go below or was back at the dock. I'll try to post a Pic when I can figure out how.
Dave
 

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You're a bit confused I think... we're mainly talking about how to mount the transducer, whether it can be transom mounted, shoot through the hull or if it needs to be mounted through-the-hull.

On my second boat, I mounted it on a board that flipped out into the companionway when I was sailing. It folded back in when I needed to go below or was back at the dock. I'll try to post a Pic when I can figure out how.
Dave
 
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