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east tx skier
08-02-2004, 04:08 PM
I've been reading of more and more people installing fish finders on their ski boats to warn them of boulders and stumps (even when they feel they know the lake like the back of their hand). Anyone tried this. Is is something you actually have to install, or is there a handheld variety that is equally effective. Also, if you have to install them, is there a less permenant way to do it rather than drilling holes or the like?

DanC
08-03-2004, 12:01 AM
Great idea Doug. :)

Here on the California Delta, sandbars shift location every year, the dredgers move things around, etc. And the California lakes' water levels are so far down that some people are canceling houseboat trips. Others are loosing their underwater gear hitting islands 300 feet from shore. This goes with the current thread about marking hazards on your waters. Not many people have seen the lakes this low so emerging points and islands are rarely marked. I think it would be a slick idea to be able to map out "today's" ski area with a fish finder. They have temporary ones that just clamp on to anything such as an electric trolling motor (could clamp to a swim platform). Even "disposable" ones with a wristwatch display and a wireless transducer that looks like a fishing bobber (boober, bober? whatever). Two slow passes and you would have your ski run mapped out. I will have to start looking into this.

H20skeefreek
08-03-2004, 06:22 AM
I've been reading of more and more people installing fish finders on their ski boats to warn them of boulders and stumps (even when they feel they know the lake like the back of their hand). Anyone tried this. Is is something you actually have to install, or is there a handheld variety that is equally effective. Also, if you have to install them, is there a less permanent way to do it rather than drilling holes or the like?


nice idea, in theory. the problem with fish finders/depth finders is that in shallow water especially, by the time it finds a boulder or sandbar, you are already on top of it. you see, the transducer (eyes of the finder) has to be mounted in the rear half of the boat to make sure that it will always be in the water. it shoots out a cone shaped "beam" that penetrates the water. the angle of this cone is typically between 8 and 20 degrees. you could do the geometry, but at 4 feet of water, that cone is not reaching the front of the boat. Granted it will warn you of an increasing incline, but those areas are not usually what is the concern, it's a big boulder out in the middle of no where. Some of the new humminbird Matrix series have like a 60 to 90 degree cone, which might be a little more helpful.

I have customers that are looking for this everyday, but to achieve a level of "warning" for hazards, you need what is called a forward looking sonar, those are about 1200 bucks and don't work at high speeds.

east tx skier
08-03-2004, 10:15 AM
H2O, do they tend to work a little better in deeper water? Dan, keep me posted on your search. My close lake is wide open and deep, but needless to say (given my recent oops), the lake on which I prefer to ski has a few non-liquid things in it.

DanC
08-03-2004, 11:35 AM
I understand sonar very well and had no illusions of using a fish finder as a high speed warning device. My thought was that when going to a strange lake, when you haven't been to a lake since the water dropped 50 feet, or after the winter rains have moved the sand bars on a river, you could map out the bottom with a few slow speed passes with a fish finder. When I say slow speed passes I mean idle speed. In about 15 minutes one could chart out that new cherry cove just created by dropping water levels.

Doug, you say you have read about this? On the ski boards? What do they say?

east tx skier
08-03-2004, 11:43 AM
That was my plan, too. There was a thread on the Malibu Owners Board about it. What resonated with me was the comment (paraphrased), "... nothing like having a boulder pop up on that screen to remind you why you bought it."

DanC
08-04-2004, 06:04 PM
Did a little research today and also went to West Marine.

Most inexpensive fish finders use a 24 degree beam transducer (all the ones I looked at anyway).
Multiple beam transducers can have 6, 24, 60 and/or 2x45 (90) degree beams (sometimes "multiple beam" refers to different frequencies for shallow vs deep water so watch your terminology)

Floor coverage for the beamwidths is as follows

24 degrees = 2/5 of depth
60 degrees = 1.15 x depth
90 degrees = 2 x depth

So for the $89 depth finder that has a 24 degree beam; if you are in 10 feet of water, you will be looking at only 4 feet of floor (not even the width of your boat). :mad:

For the $299 depth finder with a 90 degree beam; if you are in 10 feet of water, you will be looking at 20 feet of floor. :)

So it seems to me that for what I want to do, the inexpensive, 24 degree beam fish finder will provide no more information than my digital depth finder. :noface:

The one guy on the M@&$%u site that seemed to know something used the Hummingbird Matrix 37/35 with a 90 degree beam.

Hey Doug, wasn't there somebody on the old site that worked at West Marine? How about a little help dude?

H20skeefreek
08-04-2004, 10:05 PM
Did a little research today and also went to West Marine.

Most inexpensive fish finders use a 24 degree beam transducer (all the ones I looked at anyway).
Multiple beam transducers can have 6, 24, 60 and/or 2x45 (90) degree beams (sometimes "multiple beam" refers to different frequencies for shallow vs deep water so watch your terminology)

Floor coverage for the beamwidths is as follows

24 degrees = 2/5 of depth
60 degrees = 1.15 x depth
90 degrees = 2 x depth

So for the $89 depth finder that has a 24 degree beam; if you are in 10 feet of water, you will be looking at only 4 feet of floor (not even the width of your boat). :mad:

For the $299 depth finder with a 90 degree beam; if you are in 10 feet of water, you will be looking at 20 feet of floor. :)

So it seems to me that for what I want to do, the inexpensive, 24 degree beam fish finder will provide no more information than my digital depth finder. :noface:

The one guy on the M@&$%u site that seemed to know something used the Hummingbird Matrix 37/35 with a 90 degree beam.

Hey Doug, wasn't there somebody on the old site that worked at West Marine? How about a little help dude?

Dan, I am the West Marine guy. I'd be happy to answer any questions you have, but that little tidbit you just shared about the floor area is better that what i could pull out of my hat. Lookin' for a job?

Leroy
08-04-2004, 10:29 PM
I'm clueless on these devices, but if they can point down and judge distance seems like you could put the transmitter in the water and point the transmitter to look ahead so to speak and see what is coming at the boat. Especially seems like you could do this with the bobber type devices. If you put the transmitter on pole, say 4 ft in water and pointed forward seems like you would just see the bottom from the side view.

Anyone have one that can experiment?

east tx skier
08-05-2004, 10:28 AM
Dan, I went back and reread the post. The guy was using a Hummingbird Matrix 35 (now the 37 I think). 90 degree beam.

I think the Matrix 37 runs around $300 if memory serves.

DanC
08-05-2004, 01:34 PM
Thanks H20Skeefreek.
Leroy, you've got the right idea. That is what the Hummingbird Matrix 37 does except it does it to both sides instead of forward. I spent some time reading the manual and looking at one at West Marine last night (store price $299 so Doug your memory checks out ok for today). The Matrix 37 has a regular transducer down the middle and two side looking 45 degree transducers. With the transducers set at an angle, the geometry is difficult to interpret (H20skeefreek mentions the terrain mapping sonars that do have the signal processing abilities to do that, $k bucks). It is hard to explain the display and it took some mental gymnastics to read the side looking displays. No depth numbers are displayed to the sides because the "depth" to the sides requires interpretation. It will help tell you which side of the boat the fish are on (as if I care :rolleyes: ).

I don't think forward looking is much help for a ski boat. Since I'm only concerned about water 0-10 feet deep the range of forward looking is only going to be 20 feet at best. At 20 mph the boat is traveling 29 feet per second, not enough warning to help. So what I really want is a wide beam and wide coverage for idle speed mapping of unknown territory. The Matrix 37 may do that and the transducer can be installed as a shoot-through-the-hull but at $299 the funding requisition may lack adequate justification.

east tx skier
08-05-2004, 02:19 PM
Quite frankly, I'd prefer a temporary transom-mount setup, and keep the thing in the glove box after I'd mapped an area. So, Dan, are you saying this thing maps to the side and only slightly forward?

Dan K
08-05-2004, 02:39 PM
Dan,
Just build a business case that it can be used for treasure hunting (risking the start of the pirate thing again) :rolleyes: , that should prop up the requisition.

east tx skier
08-05-2004, 02:43 PM
8p Totally forgot about the pirate thread. How'd that start again.

Also, completely misssed the point of your response because I was laughing about the pirate thing.

I cite the pirate tangent as the point when this board ceased to be about MasterCraft, and started being about the people who own them.

DanC
08-05-2004, 02:45 PM
Doug, I think so. It has a dual 20 degree/60 degree transducer straight down. Even in the wide angle mode it's look forward range is only about equal to the depth of the water.

I was thinking of mounting the transducer and power cables but keeping the display in the glove box until needed. There have been times houseboating when I wished I could do a quick recon of a cove or channel. Putting in the power cable and just tie wrapping the transducer to the swim platform sounds like a good way to go also.

Dan K, I don't think my wife would let me bring home anything I found on the bottom of a lake :purplaugh .