Depth and 360 degree imaging below surface F36 tricabin

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baggins
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Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

Hi Everyone,

Im new to the forum and I cant imagine this has not been discussed but after reading the fish finder and depth finder posts none seem to get into this type of solution please redirect me if I missed something.

I have just bought (last fall) a 1976 F36 Tricabin it has land radar but nothing at the moment for depth and visibility under the water line.

I have to move the boat from its current location to its new home through approx 300 NM of locks and some what shallow at times, rivers and lakes.

Because I'm new to a boat of this size I may be a little over zealous but I really don't want to hit anything. So I'm trying to get as much visibility below the water line as possible.

The best solution I have found is the following which I believe would provide good depth and imaging at low cruise and low speed out front of the vessel.

"HELIX 10 CHIRP MEGA SI GPS G2N" and the on a Y cable "AS 360 TM" which would provide SSI and 360 degree imaging for approx 300'.

I would mount both transponders at the back of hull of the transom.

I did read about mounting a second transducer in a bag of water or epoxied to the hull near the bow but this did not seem to give the same level of imaging out front of the vessel.

I should also add that we will be doing a lot of diving of the vessel so the increased imaging is a benefit for the diving but my main concern is object avoidance.

Any and all ideas are welcome.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by WayWeGo »

Some manufacturers have transducers designed to mount in the bow that provide forward looking sonar. For example: http://www.simrad-yachting.com/en-US/Pr ... rwardScan/
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

Hi, thanks for the reply,

Simard looks like it would do the job I will follow up and get a pricing comparison once I figure out the module list.

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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by larryeddington »

I have a Hummingbird 1198Si with dual transducers mounted amid ships about centered on side of motors. They feed a Y cable to the head. Dual ducers needed as keel will interfere. The system works fine and I almost get a video of the bottom. If you mount on transom the prop wash and in my case underwater exhaust in the F36 Tri would impair its usefulness due to cavitation and bubbles.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by GrumpyDuck »

Are you planning to pull boat out of the water to install a new transducer? If so then I would recommend a thru-hull mount transducer forward of your mid-ship line. Lots of choices for hardware depending on what kind of GPS/MFD unit you have or want.

If the boat has to stay in the water your options are somewhat limited. The Airmar P79 is a shoot-thru hull transducer that doesn't require any below the waterline holes. Installation is fairly simple. I'm using one with a Simrad EVO2 MFD and it works. All I care about it depth though, structure detail isn't important to me. Some pro tips here if you install one: http://themarineinstallersrant.blogspot ... epair.html

Just my opinion but your best bet for avoiding underwater obstacles is an up to date chart with high level of detail. All the forward looking sonar in the world won't help if you're way outside of the channel and don't realize it.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by oil&water »

With the solid glass bottoms in our boats, you will be just fine epoxying or caulking a standard transducer to the inside of the hull. Pick a place for the install and temporarily fasten in place for a test run. If it performs well, finish the job and go boating.

My electronics mentor was a sonar tech. He never mounted one outside the boat.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by captainmaniac »

Good post! Hope someone has a good solution! Just re-proofed my post... gonna be long... but hopefully extremely helpful!

I have been keeping my eye out for a good forward scanning sonar for years, but have never found a system that really works the way I want it to. Several companies make side-scan sonar systems targeted more to the fishing market... I don't give a crap what's beside me -- I wanna know (critically) what's under me, and if at all possible what's in front of me!
WayWeGo wrote:Some manufacturers have transducers designed to mount in the bow that provide forward looking sonar. For example: http://www.simrad-yachting.com/en-US/Pr ... rwardScan/
Looking at Simrad's specs, "Nominal forward view is 4-5X your current depth e.g. At 3m (10ft) depth, see 12-15m (40-50ft) ahead". Assuming you are in 10' deep water, at a typical cruise speed of 18 knots, you cover 30' per second. If the system picks up a shoal, rock, tree, waterlogged and submerged utility pole, picnic table, or 100 gallon steel drum in front of you -- you have about 1.6 seconds to STOP the boat or sufficiently change direction from the MOMENT the system shows the blip ont the screen. Ain't gonna happen.

Even in 50' of water, nominal view is only 250 feet ahead. 8 seconds from the time the sensor first picks it up. How many of us look at our depth sounders or chart plotters every 8 seconds or less? Especially in 'known' or 'local' waters?

I'm looking for a much more useful forward looking system (1000' plus), potentially with depth alarm capabilty to signal when a registered bottom or other obstruction is within X feet of the surface within it's scannig range, to give you lots of time to slow, stop, or change course to avoid it. I would also like to see something 3-D in the sense that it doesn't just focus on a very thin scan ahead - but gives a 3-d perspective of what you are coming up to perhaps up to 45degrees to each side of dead ahead... to help you figure out how best to avoid a potential obstacle. This has to exist at resonaboe cost somewhere.

[30 years ago I developed software for the Canadian Center for Inland Waterways to render collected soundings as a 3D topolocical view of the bottom, leveraging an advanced predictive algorithm, to help cartographers figure out what soundings were likely to be most relevant when creating or updating charts. 5-10 years ago GPS companies came out with 3-D renderings of bottom contours - 20 years after I already did it... At this point, 30 years after what I did, mass market companies technology and capabilty HAVE to exist to satisfy my desired forward mapping cabilities, by now!!! I just can't find anyone using those technologies!]
GrumpyDuck wrote:Just my opinion but your best bet for avoiding underwater obstacles is an up to date chart with high level of detail. All the forward looking sonar in the world won't help if you're way outside of the channel and don't realize it.
On the contrary... I have charts and use them. Yes, in most deep or shallow water situations, charts are your best friend (as long as they are current). I want to use forward scanning sonar to find stuff that is NOT ON the charts... as cartographers don't map ever single inch of the bottom... and other stuff happens over time (boat sinkings, people dumping stuff, storm remnants (trees, utility poles, picnic tables, etc...), harbour entrances or confined channels silting up, etc... And if you ever find your way out of a channel (on purpose or by mistake) -- a good forward scanning sonar may help you avoid catastrophe.

Note -- many years ago (different boat) I found myself 'outside the channel' by about 15-20 feet. When I saw the marker and realized I was out of the channel, other boat traffic coming up behind me made it too dangerous to try to cut back in to the channel because of potential risk of collision, so decided keeping my course and cutting as close to the marker as possible was my safest course of action. Wrong apparently... The channel was 200' wide, and the river was 2000' wide. I was less than 20' (1% of river width) outside of the channel -- lost the bottom of one stern drive (and SS prop) and half the skeg off the other drive ion a shoal, that was apparently within 2' of the surface.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by WayWeGo »

I suspect that forward looking sonar that will give you an accurate return 1,000' ahead of your boat in shallow water is not likely to happen anytime soon. There would be too much scatter in the signal that would get reflected back and make resolving targets very difficult.

On the other hand, the forward looking sonar that is available today can help when running at hull speed and below. It would be especially effective when navigating shallow water that is murky or at night when a lookout on the bow would not be able to see anything. Entering an anchorage protected by a shallow winding channel would be one application. Avoiding sunken wrecks, stumps, fish traps or other anomalies that are not charted would be another.

The downside is that the transducers are expensive, so until they come down in price or I have a more pressing need, they will remain on my list of interesting technologies that I follow but am not ready to invest in. Maybe later when we cruise the Great Loop or ICW I might see this differently.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

Thanks for all the feedback,

I sort of took a grain from all the posts.

And took the plunge (literally) and hope to goodness it was not an expensive mistake. I just completed phase 1.

Keep in mind the water in lake Simcoe at the moment is very very cold but no fish were harmed (so far) during the making of this solution.

So I did tones of research (flipped back and forth) and read all the posts and finally decided that what ever the limitations I really needed/wanted forward looking sonar and as I'm not a experienced angler who is used to reading standard sonar fish finders I decided I really needed 3d and also decided that regardless of the short delay to respond to an object some delay was better that none.

I also found that gps and chart plotters occasionally show me boating down the grassy verge next the channel when clearly I'm 10 feet to the left. So i really want to see whats out there and if I can avoid great, if I can't and hit something at least I will know I did my darnedest; and as mentioned my first trek with boat is going through 400 miles of waterways, lakes, locks and rivers I have never seen before.

So that said I choose the following and I will come back and let you all know how it all goes.

Phase 1: Decide and buy a solution. (complete)
After many conversations we many sales reps, boaters, forums and tech support I decided to purchase the following:
1. Garmin 7607xsv
(the reason i only got a 7' is because these things are freaking expensive and I can display the screen remotely on an 18" tablet using Garmin Helm)
2. Garmin PS31
(this provides true foward facing 3d, its very very nice, however you have to get over feeling very very sick about the price (and have a very supportive/understanding wife))

Now you might say, this will never work with in boards but I have a plan (how good it is will remain to be seen). Basically I have received and tested everything in the following manner.

I rigged a wooden test mount for the transducer so i could test the transducer at different places around the boats rear end. Obviously at most places from the center out to about 10" from the sides cavitation and bubbles at even slow speeds led to issues. However from the sides moving forward to where the rear cabin starts yielded very very impressive results. I am back home now but next weekend will share some screen shots but its really cool.

I'm a diver (usually in warm water) so after the tests I investigated the correct location on the keel to attach the transducer just forward off the props.

So on to phase 2.

Phase 2: (in-progress, please advise if you have constructive input)
Attaching the transducer to the boat:

So I have deiced to fasten the transducer to the keel in the location I have discussed, but as many of you might mention (and based on the posts already) i have decided to the following:

I have access to some 1" thick white plastic its very strong material very similar to commercial cutting boards so am going to cut a strip as wide as the keel and about 36" long. I will pre drill wholes on counter sink washers and stainless bolts in several locations on the plastic strip so that if I'm wrong about the location i will be able to move the transducer mounting hardware further forward. This will also allow me to remove the transducer if needed for transport/repair.

I will also be attaching security cables to the transducer mounting hardware to the plastic strip just in case the mount has issues; I hope this will prevent the transducer from being ingested by the props.

I am going to epoxy the strip of plastic to the keel underwater using wet dry 700 which I have been told (by the vendor/manufacture) is designed specifically for this sort of thing, I need to do some tests to make sure the epoxy works with the plastic and fiber glass under water which will be done this week in our fish tank, the empty one.

Once confirmed the epoxy works I will attach the plastic strip to the keel on the boat (I have thought of using oak or teak or some wood but as long as the epoxy works the plastic I believe would be the best) any thoughts ?

Phase 3:
Attach the transducer. I will used the designated bolts to bolt the transducer mounting hardware to the pre drilled plastic strip containing the bolts, i may need to retap the bolts if epoxy has made it in to the threads but I do plan to use tape on the underside of the nuts to prevent this.

Given the epoxied surface area of the plastic on the keel, the strength of the plastic and mounting hardware I'm hoping this solution will work and last until haul out in the fall and then we will decide what to do if anything needs to be changed.

Please understand that at the current marina a haul out would cost almost 1500$ and cant be done until June as its silly season for the marina. And even if i did haul it out i would do the same thing (all be it with out the diving in freezing cold water).

Of course if it doesn't work I will likely face some public humiliation but at least I will have tried and maybe many will find this experiment useful.

P.s. the Garmin on the 18" tablet is fantastic. And over all the solution was not much more than the 12" hummin bird/360 solution.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by prowlersfish »

How are you running the transducer cable ?
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by captainmaniac »

Just wondering about possible issues with your antifouling paint... essentially it sounds like you will be epoxying the plastic to your painted keel... If you are running an ablative paint I would wonder about the epoxy job failing.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

@captainmaniac: I was planning on removing the anti-fouling prior to application of the plastic strip and epoxy using a dry wall sanding sponge (they do very well when wet and can sand evenly on pretty flat surfaces), On dry land at least they remove anti fouling well. Of course in the water might be a completely different matter. I should also mention i will be doing this work at a beach in approx 5' deep water and a sandy bottom so while I will be in full diving gear i should be able to put some elbo grease into the sanding job while kneeling on the bottom.

@prowlersfish: I will epoxy cable hooks every 1' feet along the keel to the transom and then run the cables (power and the Ethernet) through the cable hooks and ty-rap them in place. I have yet to find the cable hooks I'm going to home Depot tomorrow to do some scouting but they need to be plastic, strong and compatible with the epoxy. I will have to extend the power cable. My plan is to run up the center of the transom and into the starboard rear storage compartment on the rear deck and in to the starboard engine bay for power and Ethernet connection to the fly bridge.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

I should add, that i explained the process for the gel coat prep and anti-fouling removal to the guys that distribute wet/dry 700 and they seemed to believe this would work but suggested i do a small test piece before i do the large 36" piece so i plan to use the cabled hooks for the test, apparently it will either work really well or not really work at all.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by baggins »

I will write a complete detailed process and post it here just in case any one else wants to try this.
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Re: Depth and 360 degree imaging below surface F36 tricabin

Post by prowlersfish »

Why not just use a transducer that can see thu the hull ? You may be able to use yours and mount it inside the hull
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