depth sounder advice

[george]

I need a depth sounder. Some book I read said it was the most important bit of electronics on a boat so I figured I would get one of these next.

I already have a handheld VHF, and have wired my mast for a mounted one.

I have a handheld GPS (garmin legend).

What would you use for a simple depth sounder? The boat is out of the water and has zero installed electronics, but not for long.

1) I am scared to cut a hole in my hull for a thru-hull transducer. Seeing how Tim did it made me wonder what happens to the wood block he used as fairing? Do you cover the wood with epoxy? It seems extreme when all I care about is if the water is getting too shallow.

2) Has anyone used a shoot-thru transducer for a depth sounder? For reason #1 I would prefer one of these I think, but not if they stink. I have seen some with fish finders, but I don't plan on doing a lot of fishing. Or should I get a fish finder instead of the old-school depth sounder like Tim has?

3) Do I really need an external antenna for GPS units? I have read the internal antennas can pick up through fiberglass but was wondering what others have heard. The external antenna looks like a giant bulbous sore in my opinion. Why is it so big and the internal ones so small? Price justification?

I am about to blow a lot of $ on finishing the dream. Help me spend it wisely!

Thanks for your continued guidance.

[Tim]

I need a depth sounder. Some book I read said it was the most important bit of electronics on a boat so I figured I would get one of these next.

Well, they're sort of handy, but I wouldn't call it the most important piece of electronic equipment. But they are nice to have.

What would you use for a simple depth sounder?

Use whatever you like and what fits your budget. There are many, many, many choices, between depthsounders and fishfinders. Don't get anything with one of those external transom mount transducers, because those won't work on your boat. You need a puck or mushroom transducer.

...what happens to the wood block he used as fairing? Do you cover the wood with epoxy?

Wood is fine under water. I think there are one or two boats built of this material, but I'm not sure.

Lots of people mount their transducers inside the boat. There are quite a few threads on that subject here on this forum, I think. Plenty of good advice to be had.

Do I really need an external antenna for GPS units? I have read the internal antennas can pick up through fiberglass but was wondering what others have heard.

It doesn't matter what anyone has heard. What matters is what works. The newer handhelds sometimes work indoors and under cover, but all GPS units really require a view of the sky in order to work best. I wouldn't ever want to stake my ability to navigate on a GPS working properly indoors.

How do you intend to use the GPS? If using it mostly on deck, with occasional use below, is what you intend, then you may not need the external antenna. You only really need the antenna if you plan to permanently mount your GPS belowdecks. If you're using the handheld like a handheld, you may well not need the external antenna.

What I'd do is this: use it without the external antenna. If, during the sort of use you anticipate, you find you need the antenna, then get one and install it then.

[Figment]

I am about to blow a lot of $ on finishing the dream.

Yes, you are! And good on ya for embracing that right from the start! The first step to recovery is admitting you have a problem. Hanging around here may not really help the whole "recovery" thing, but it sure is a fun place to further one's understanding of one's addiction.

With that in mind, look at this depthsounder issue through your "It's All Connected" glasses. Is this depthsounder really going to remain a stand-alone unit, or will it eventually become part of a more comprehensive electronics package? I recently rode this roller-coaster myself. All I felt I really NEEDED was a depthsounder, but that same hole in the hull can also report on speed, and the same processor that handles the depth and speed info can also read windspeed from a masthead, and in the blink of an eye I'd talked myself into spending 3x as much, but hopefully also getting 3x the value for that money, because It's All Connected.

1) Don't be scared. I can't remember ever hearing about a boat sinking because a transducer failed. I'm sure such cases exist, but they must lag far far behind failed hoses and other real hazards.

2) I'll let someone who's done it themselves chime in, but my impression s that it's a fairly well-proven practice.

3) Ever tried using your handheld from within the cabin? Yeah, they can pick up through fiberglass, but they pick up a whooooole lot better when they can see the sky (and the satellites beyond). I agree with your "bulbous sore" comment, and I share your doubt of the price justificaiton. I'm sure that this is at least 50% of my happiness to stick with my barebones handheld gps.

[Robert The Gray]

I myself have a basic depth sounder on my boat. On my last boat I became quite adept at throwin' the lead from the lee side while sailing along. I could usually tell when the gradual silt mud flat bottom of the bay around here was starting to shoal up. I would never know if a rock was ahead of the boat. I can't do this on my depth sounder now. It just gives a number with which I must then do arithmetic upon. Transducer is below the water line, with a draft of 4' something I am on the mud at 3' 11'' on the dial. I do like to have the depth sounder because I cannot see the bottom in our waters.
With regards to fish finders I am thinking of mounting one with a non-hull penetrating transducer. The view on the screen is much more detailed but I am unsure how much of a forward look they will give. I have been thinking this winter about fishing. The herring are now in the bay and on those light days I can jig for some. In the summer I can catch salmon. We have a problem with heavy metals in the bay and the only fish that are really safe to eat are herring and salmon. The bass, the flounder, the rays, the sharks, the sturgeon, and even the pan fish have limits on how much you can safely eat. Those herring are quite nice grilled up on the george foreman. Using a sailboat for a fishing platform requires some mental shifts, but it is just nice to be out on the water regardless and if you can capture some fresh protein at the same time.....
I think fishing is as old as sailing, lots of craft there. I wouldn't ruin a great sail to catch a fish but if the wind is light it passes the time.

r

[Shoalcove]

I installed a new Raymarine ST60 depthsounder in a couple years ago. Since the old one failed one week after launch I decided to mount it inside the hull using some ABS pipe filled with mineral oil. I just stuck the pipe on with 3M 4200 since it was just temporary... Works great! I'll probably knock out the old transducer and fill the hole this spring and stick with the present set up. BTW, I was gagged by the price but the ST60 works very well and (very importantly to me) has huge numbers that are easy to read. A fishfinder often has small numbers that are harder to see if mounted a ways away. Have fun

[Columbia34]

On the GPS topic we are looking at the Garmin 498 Chartplotter with internal ant, well we are waiting for the 2007 stuff to get released cause its going to be in 3d for not much more $$$. Back to me question will a internal ant work through a canvas bimini top?

Scott

[Peter]

1) I am scared to cut a hole in my hull for a thru-hull transducer.

George:
I have a Huminbird fish finder/depth sounder. I followed the advice from others with Albin Vegas like mine, and simply stuck the transducer to the inside bottom with a big glob of Sikaflex 291. I was sceptical, but it works like a charm.
I too dislike drilling holes through the hull!

[catamount]

I got a Garmin Fishfinder 140 and epoxied the "transom-mount" transducer inside my (solid fiberglass) hull. No holes, Good depth information together with the bottom profile, bilge temperature, and system voltage, and actually less expensive than other more traditional sounders. I have shallow/deep alarms, etc... but the one thing I don't have is the ability to set an offset -- the fishfinder is reporting the depth from the transducer to the bottom, not the depth from the surface of the water to the bottom. On some sounders you can enter an "offset" value so that the reported depth values are from the surface.

[Duncan]

epoxied the "transom-mount" transducer inside

Am I ever glad you posted that!
I ended up with an odd assortment of Raymarine gear that includes one of those, and now I'll be able to use it!
(I guess I could have figured it out, but it never occurred to me.)

Thanks very much.

[Tim]

I'm still amazed that it works to install a transducer inside the hull, but so many people are doing it and reporting complete success that I guess I'll have to look into doing it that way the next time I install one.

So many "rights" can't be wrong. Right?

[Mark.Wilme]

Is it safe to assume that mounting the traducer will work only if the glass is solid. I would think that if the glass were to have voids in it (airpockets etc) or to have a core material (unlikely below the waterline) then I would suspect results would be less acceptable.

[CharlieJ]

Definitely Mark. If the hull is cored, it will not work. If ther are voids or air bubbles where you choose to place the transducer it will not work. On Tehani we had to put the transducer off to one side a bit becasue apparently there was a small void in the layup right on centerline. I wound up putting it inside a PVC pipe cut to fit the hull and capped, filled with mineral oil.

It's a simple job to test it- get a large baggy, fill it with water and lay it down where you want the transducer. Put the transducer on top of the baggie- no need to put it inside, and move the whole thing around till you get a good signal. Drop the transducer over side to get a solid read first so you'll have a benchmark. When you find a good spot,, with a good read , glue it down. Humminbird recommends epoxying it in place by the way. I discussed this subject with them one time.

Bear in mind you WILL lose a bit of capability- if the sounder normally works to 400 feet for example, your's might quit at 375 shooting through the hull. But shallow water response is still good and that's what you want to know most times anyway.

By the way- I threaded a 1/4 - 20 pan head screw into the top of that PVC cap so I could add the mineral oil-- I use a syringe and squirt it in. A second 10-24 or 10- 32 hole would be nice to let the air out as you filled. It's a slow process without that air hole .

[Mark.Wilme]

Lets face it,most of the time we are not looking for depth finders are we ? We are looking for shallow finders.

Do we really care whether there is 374ft or 400ft under our keels ? Unless we are trying to use soundings to determine position

[jpmathieu]

[quote="george"]I am scared to cut a hole in my hull for a thru-hull transducer.
quote]

When I purchased my renegade in 94 It had a thru hull transducer forward of the keel mounted in a flat spot, which may have been molded into the hull for this purpose. Anyway the sounder and thru hull were shot so I replaced them with a standard horizen setup. When I removed the thru hull I found it was about 1/2 inch smaller than the new one. I had to redrill the hole. If my memory serves me I went thru at least 1 1/2 of hull in that spot. I don't recall what I sealed the hole with, but I don't remember resin being involved. I think I used 5200. I can safely say the thru hull is still there and as far as I know it has never leaked. It still works fine.