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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

depth finder

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georgiaboater
1st Mate

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USA
72 Posts

Initially Posted - 12/28/2006 : 22:10:28

Has anyone recently installed a new depth finder on their boat.? I am particularly interested in the 1978-84 model years of boat and the newer digital read out type. If you did this successfully, where did you place "sounder". The instructions seem to suggest at a point forward of the swing keel, but I am not sure where that would be in terms of the"thinnest" point between the cabin floor and the exterior haul surface. Another way, I guess, is on the little bracket provided for mounting it at the bottom of the external stern.

On the other hand...has anyone replaced or repaired the original equipment (depth finder and speed indicator) located just to the right of the companionway going into the cabin.

Marshall P

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Alan Clark
Captain

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406 Posts

Response Posted - 12/29/2006 : 07:45:19

Marshall, If you do a search on signet marine you will find the question Iposed and the results of our and others getting their signet marine knot meter and depth gauge repaired. I am re-installing ours today in the boat..sadly about 100 days to launch!

Fair Winds

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Brooke Willson
Admiral

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USA
983 Posts

Response Posted - 12/29/2006 : 08:23:10

Marshall, on my '85 swing keel, the transducer ("sounder") is located just forward of the door below the v-berth, and just aft of the head sink through-hull. The wires run starboard below the sink, below the starboard settee, and then to the readout on the starboard cockpit bulkhead. It works quite well there. If you do the search Alan suggested or other searches, you will find instructions on how to mount a transducer without cutting a hole in the hull (although mine is cut through).

I've replaced my readout twice -- assuming the new one is compatible with the old transducer, you just remove the old and plug in the new. By the way, there's no standard location for any gauges or compass on a C25: yours is there because that's where a previous owner put it!

Brooke

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 12/29/2006 : 08:29:58

Marshal,

I went through this when my boat was new. I read somewhere that a depth sounder (the transducer)makes no sence anywhere on the boat except as close to the bow of the boat as possible. The reason of course is that you want to know where the shallow water is before you run your keel up on it. I drilled the first hole in my hull just forward of the v-berth bulkhead. The hull just starts to form a "v" at that point so I had to use a little more caulk to fill the void, but I've never had a leak. That was 17 years ago. Today I think I would use the wax ring method and not drill the hole if I could get a good depth reading.

As far as replacing or repairing, check with the manufacturer. When I had to replace my Standard Horizon speed and depth instruments after a lightning strike, the company did't make/repair the model I had but offered to sell me the latest technology at manufacturer cost. I couldn't pass that offer up so I bought them. The transducers fit perfectly in the holes I had previously drilled.

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djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 12/29/2006 : 10:03:58

I mounted my sounder against the rear bulkhead of the compartment under the V-birth. And as you can see from the pics below, this is were I mounted my Garmin 172C and Garmin 160. Cheers.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 12/29/2006 : 11:50:54

As for mounting the transducer as far forward as possible, I wouldn't worry to much about that. If there's a sudden drop in depth (such as a rock), when it's picked up by the transducer, you're already toast. If you have an old transducer, you might want to use that hole rather than cutting a new one and plugging the one you have. The fewer holes in the bottom, the better.

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millermg
Navigator

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159 Posts

Response Posted - 12/29/2006 : 13:11:46

The reason manufacturers recommend installing transducers near the bow is to get them ahead of the keel- the turbulence in the water aft of the keel can throw off the accuracy of the unit. Also important is to get it as close to the centerline as possible, so that the unit sends straight down, as the curve of the hull will change the angle of the signal and give you "optimistic" readings!
That spot Al mentioned is pprobably the best spot- just behind the intake thru-hull for the head under the V-berth. I've got both depth and speed installed there, and the access for servicing them is good.

Edited by - millermg on 12/29/2006 18:02:55

djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 12/29/2006 : 13:47:48

As far as being level, when I mounted mine, the bottom of the compartment was sloping so I leaveled it with the rear bulkhead of the V-Birth compartment. But I agree, If I am doing 5 knots, I'll hit ground before I can react so being in the front or back does not matter too much. I was thinking of gunkholing. If I go into a small harbor very slowly, I wanted it as far forward as possible. Cheers.

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 12/29/2006 : 14:37:13

Agree Dennis, I'd rather see the bottom shallowing ahead of me. Usually I'm in slomo when in close quarters and need to check he depth. Otherwise I'm using a chart and/or my chart plotter.

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djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 12/29/2006 : 18:21:20

Idealy, I would have my wife (naked) on the bow with the boat hook checking depth but I have too many situations by myself when I was going into shallows. Cheers.

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georgiaboater
1st Mate

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USA
72 Posts

Response Posted - 12/30/2006 : 22:30:07

Thanks for everyone's great response to the depth guage/transducer question. I guess my only other question at this point is the installing/testing. The instructions would seem to indicate that one can do this with the boat out of water/on the trailer. How exactly is that done? Thanks again.

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OLarryR
Master Marine Consultant

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USA
3502 Posts

Response Posted - 01/02/2007 : 08:55:00

My website has install details for a Humminbird Fishfinder with transducer installed in-hull using a toilet bowl wax ring. This was installed near where the original hull thru transducer was installed under the VBerth area. Works fine. I like the seeing a visula image of the river bed contour which the fishfinder provides based on transducer readings.

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Trust Me
1st Mate

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USA
71 Posts

Response Posted - 01/06/2007 : 04:42:04

Marshall:
I have the Standard Horizon depth sounder which allows me to set a depth alarm. In the base set up process I added a 2 foot "offset" to my zero depth settings to essentially lie to myself

on the display so when it read 0.0 depth I really had 2 more feet beneath my fixed keel (4 feet below sounder unit). When slowly motoring along a strange shore or easing into a silted harbor entrance this has saved me a few times (not always) from sticking the keel in the bottom.
I do not agree with Dennis' naked lady approach as any gauge monitoring would be a lost cause under those circumstances.

Capt. Ron
On the hard and watching Cruising the South Pacific videos for withdrawl treatments

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OLarryR
Master Marine Consultant

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USA
3502 Posts

Response Posted - 01/06/2007 : 08:31:59

Capt. Ron,

I was giving this somethought about my own install with the in-hull transducer in the VBerth area and actually there is some conservatism with most of our installs, that is, with reading accurate depths. This is because IF the transducer and depth finder/fish finder are calibrated accurately, then at the VBerth area, they are already below the waterline a bit...perhaps 1- 1 1/2 feet. So...when the depthfinder reads 3', it is probably more like 4 1/2 feet.

I have checked my fishfinder readings with against measuring how far I hit the depth using a stick over the side. There is about a 2 foot difference which I believe is partially because of grass/sediment on the bottom giving a shallower reading on the fishfinder plus the fact that where the fishfinder is mounted, it is closer to the sea depth.

Generally, when the fishfinder reads 4-5', I tack. Sometimes, especially in very familiar waters, I will wait till it hits 3 feet (3 1/2) feet and then tack. I suspect, even in those instances between grass/sediment and the transducer in the VBerth area, I am probably in closer to 5+ feet when it reads 3 1/2 feet. Of course, have to also account for any wave action but I have never run aground since installing my fishfinder and in the river environment and areas of narrow channels, I am constantly flirting with shallow waters.

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OLarryR
Master Marine Consultant

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USA
3502 Posts

Response Posted - 01/06/2007 : 08:40:28

Reading your comment again, I guess you are really accounting for the same thing but setting an alarm to warn you when you are approaching that 2 feet extra because of where the sounding unit is located. I guess I do not use the alarm. So far, I seem generally aware of the depths and how fast it is chnaging because of the large fishfinder display showing the river contour. SO...even when I am in say 20-30 feet of water, if I see the contour taking an upward slope of say 70 degrees....you can bet I take notice of that. Also, the waters in the Potomac...I pretty much know them. IT is just a question of how low it will go depending on tide and how far out of the main channel I can go before tacking...so I have other semi-warning signs.

Setting an alarm is probably a good idea especially since most of the units have this option. Good suggestion - thanks !

By the way...I have a wing keel - 2' 10" draft.

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Trust Me
1st Mate

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USA
71 Posts

Response Posted - 01/07/2007 : 15:24:14

Larry:
I always use an alarm as I have a tendancy to take a tack to the limits of a shallow lake shore just being lazy to enjoy a longer next tack. There is the family story of my son Randy at the helm during the nationals taking us so far into the shallows to get a better angle on the next tack at a boat speen of 6+mph that the depth sounder alarm went off at 5ft. but by time we made the turn the depth sounder read 0.0 ft. To this day he claims he "knew" where that "hole" was

Capt. Ron

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