Core Sound 20 Hull #102

[wkisting]

Yes, I know... I shouldn't complain. Much of Georgia still needs rain badly, but here in the NE part of the state (on the SC border), we've had enough off and on lately that it doesn't feel like we're in a drought anymore. Certainly, the lake still has many feet yet to raise, and for a 72,000 acre lake, that means a LOT of water yet.

Good news is that this evening we finally had a break of clear weather, so I've progressed a bit on the masts. Still have to make tapered wedges for fairing the sailtrack across the tubing joins. Do most folks use wood? Or is there something else to use for the wedges?

[Norman Colter]

I feel your pain Wes,

  We had a very wet July, put me behind. But not any more. Got the registration yesterday, splash this weekend.

As for as the wedges go, I seem to remember Charlie making feathers with glass. He'll probably remind us. Have fun.

Norm

[Peter HK]

Still have to make tapered wedges for fairing the sailtrack across the tubing joins. Do most folks use wood? Or is there something else to use for the wedges?

I made glass feathers- see

http://www.messing-about.com/forums/index.php?topic=5642.msg47378#msg47378

Peter HK

[wkisting]

For my birthday today, my wife gave me one of those fancy GPS/depthfinder combo units (Lowrance 520 model), so now I'm wondering where the heck I can mount the skimmer transducer for the sonar. I believe Graham has a combo unit on his E22 -- anyone know how the sonar is mounted?

If I put the skimmer on the transom, I'm not sure if it will be constantly submerged as the directions require. (A few folks have said the CS20 holds her tail out of the water, no?)

I could maybe route the cable down the CB slot and bolt the skimmer into the side of the keel, which would mean no hole-drilling, but not sure if that's wise from a durability standpoint. And it might catch turbulence from the CB.

I could buy a bolt-through hull transducer instead of the skimmer version... perhaps that would be preferable? Even then, I'm not sure where it should be placed given that there's a keel down the center of the hull.

Any ideas? I've never mounted a sonar transducer, so I don't know what an "ideal" mounting location would be.

[tom151]

I could buy a bolt-through hull transducer instead of the skimmer version... perhaps that would be preferable? Even then, I'm not sure where it should be placed given that there's a keel down the center of the hull.

Any ideas? I've never mounted a sonar transducer, so I don't know what an "ideal" mounting location would be.

Many of the new generation sounders can be mounted inside the hull - shooting thru through hull skin - no need to penetrate the skin at all.  Check with Lowrance for the technical requirements.

The sounder I recently purchased has directions for building up a simple pad of epoxy to mount the transducer directly to the inside of the bottom of the boat. Gotta make it uniform density with NO air bubbles included.

For best performance they are usually mounted in the forward 1/3 of the hull.

Since most can also be calibrated for depth there's no problem mounting them off center - I'm putting mine inside a storage/flotation compartment.

Hope that helps a little,

[Ken_Potts]

Happy Birthday Wes!

Sorry.  I've got no useful information for you.  My depth sounder has a downhaul on it  ;D  I haven't gone electric on my boat yet except for nav lights.  Just thought I'd say Happy Birthday.

[Peter HK]

Many of the new generation sounders can be mounted inside the hull - shooting thru through hull skin - no need to penetrate the skin at all.

I'm not sure if that would work through plywood. The problem is that the tiny air pockets in wood have similar effect to bubbles - the solid/ air interface having high acoustic impedance. I have used transducers through the hull skin in a couple of large cruising boats- they only worked in areas of solid glass with a good fluid contact...on one I used a glycerine filled container that had been glued to the hull. They wouldn't shoot through various foams or even coremat which in theory is pretty well impregnated with resin. The centreboard interfered with the signal even when 2-3 ft away from the transducer.

Peter HK

[wkisting]

Peter is right about the problems with shooting through any kind of material except raw fiberglass. The Lowrance manual warns that for thru-hull applications, the skimmer has to be in contact with the outermost layer of glass, then filled around it with THEIR special brand of epoxy which is (supposedly) uniquely formulated to an ideal consistency to minimize air bubbles and facilitate good signal strength. I've only got a thin layer of 6 oz. cloth on the bottom, so I'm not sure if I could feasibly carve out the wood without going right through the bottom layer of glass accidentally. But I agree that a thru-hull mounting is probably ideal since the transom option seems to be out.

It may be easier, I think, to buy a new cable that has a bolt-through transducer. That way I'd still have the water temperature function (not necessary, but cool) and no loss of signal strength compared to mounting the skimmer as a thru-hull. But then I suppose there's a greater danger of leaks around the thru-hull.

I'll let you know what I come up with... I wish I had prior experience with these things to know how much any of these mounting considerations actually matters to performance. I'm not real concerned about having sonar that can find fish hiding everywhere, but I do want it to reliably calculate depth and (if possible) give me a reasonably clear view of the bottom conditions (hard vs. soft) for anchoring purposes.

BTW, thanks for the birthday wishes!

[Edit to add: Hey Ray, if I try the option you mentioned and add all those pounds, I'll gladly race you, but only if you agree to turn your Anderson Bailer around 180 degrees before the race. That should be a fairly interesting match.    ]

[Apteryx]

I have a CS17 I'm just starting on, and I've been musing about wiring, radios, and sounders.

As much as I sail to get away from fancy electronic gizmos, I like depth sounders.  If I do that, I think I'll go with cutting a hole in the bottom, maybe under the aft deck.  I don't like holes in the hull, but there's already a bailer and a centerboard slot.

Maybe have a battery box under the foredeck hatch, and a pvc pipe wiring run under the seats.

Nav lights that are mounted on the topsides don't impact night vision, but I'm not sure what to do about a stern light.  On a catboat I have a white stern light on the boom gallows, and that keeps it from relfecting back and messing with my eyes.  However, a transom mounted stern light would be obstructed from one side by the rudder.  Anything that sticks up could foul the mizzen sheet.

Any ideas on stern lights?

[Designer]

Wes,

I wanted a depth finder on Southern Skimmer as I knew that I would be pushing hard through the night in lots of shoal waters in the Everglades Challenge. The further forward it is in the boat the sooner you will know when it is getting shoal. I got a Lowrance depth finder with the transom mount which we installed permanantly in the forward part of the boat.

As there is a lot of signal loss transmitting through plywood, the ply was ground back to the 6oz glass sheathing and reglassed on the inside to bring back the strength. The transducer was glued to the glass. Tom did the job which shows what a superb craftsman he is.

Infant mortality claimed the depth finder before we really needed it. Lowrance replaced the unit and it has worked well since.

I have since gotten a Garmin 440S Chart plotting GPS with sounder which I really like. Because I already had a depth finder forward, I decided to mount the transducer in the bracket over the stern. I did not want to mount it permanantly because I want to be able to use it in different boats. It works surprisingly well, ventilating and losing signal only accasionally. It is mounted as close to the centerline as I could without fouling the rudder.

The down side with the unit is that it is a power hog and we now carry a small car battery and a 20 watt solar panel. It worked great on the Texas 200 and we were able to charge cell phones, cameras and VHF radios along the way. 

[tom151]

It works surprisingly well, ventilating and losing signal only accasionally. It is mounted as close to the centerline as I could without fouling the rudder.

Graham,

Just a detail... did you transom mount the sounder on the same side as the centerboard - or the off side?

[Designer]

Yes I did. The mount is about a foot from the centerline to clear the rudder. I chose that side because the wiring was already on that side. I think that it is far enough away from the board that turbulence would not be an issue. The ventilation happens when it is on the windward side and we are heeling as well as a wave passing.

[Designer]

Ray,

Aren't your reflexes that fast?

[Charlie Jones]

;D at Ray

I can quite clearly recall an evening in Southwest pass, Vermillion Bay La ( which is fixing to get rearranged sadly) when Laura and I were searching for a place to anchor for the night, in preparation for going offshore the following morning.

South West pass runs around 100 feet deep so we figured we'd find a sheltered, shallow spot along the inside of the pass and anchor up.

I was on the bow and Laura was slowly motoring in towards the shore in a likely spot. I had the anchor at the ready and she was calling out depths.

"100 feet, 100 feet, 100 feet, 85 feet, THREE"

So we bailed out and tried another spot- same routine. That pass is like a ditch. We wound up running back out into Vermillion Bay and anchoring in the open bay for the night.

I was really glad the transducer was up forward though ;D

[Apteryx]

My Core Sound is going to get fed to the wolves as far as shoal sailing goes.  Local lakes are shallow and murky, and I will likely singlehand a Texas 200 one (or two, or three, or ten...) of these years.  Next year, maybe, fingers crossed I can start in on that.

From the charts there's a lot of thin water in the West Bay behind the end of Galveston Island.  What if, in my youthful exuberance, I wanted to sail on from Magnolia Beach and pull out at, say, Kemah?  Gotta be able to pick my way through the mud banks.

There's a balance between convenience and overcomplication, but not having to fetch a handheld would be a nice convenience.  Before I close off some choice locations I'm going to consider a built-in sounder, probably a Raymarine.  It's a big nasty hole to cut in the boat, and one has to consider what a boat is really for when adding more to a wonderfully simple boat.  But the display would look cool under the mizzen thwart, right there next to the vhf, the gps, the 8-track...  ;D

The sounder will have to mount where its backside is protected, so that means either under the foredeck or the after deck.  Things are flatter aft so I may just rely on my cheetah-speed reflexes. 

[wkisting]

Thanks for the feedback guys. I'm still not sure I want to mess with installing the skimmers as a shoot-through-hull sounder, though that would be the best solution to keep it wet and protected at the same time.

I'm toying around with trying a temporary mount first... putting the transducer on a metal extension arm off the transom (or off the rudder housing) that will hold the transducer down underwater a few extra inches, but have a hinge that can kick up if it strikes something. Maybe on a light bungee cord or something so that it snaps back down into place right after. I hate to reinvent the wheel for this... but I did find out that the simpler solution of switching to an actual bolt-through transducer would cost something like $320 because they're solid bronze. Too pricey for my needs.

I'll keep you posted when I figure it out to let you know what I decided. In the meantime, if anyone has pics of their transducer setup, that would be great. I'd love to see how others have solved this problem.

[Charlie Jones]

Remember- we run our 3'3 inch draft sloop through those waters and all over around here. It's roughly 7000 pounds loaded so I really don't like going aground. But in your Core Sound, you can just hop out and push. No biggie. About the same as our little trimaran. So methinks you over worry on the depth sounder. In fact, we seldom have ours turned on until we are creeping in to an anchorage and watching it to let us know when to drop. And even then I often just let six feet of chain out, let the anchor drag along til it hits bottom, then dump it. ;D

Your Core Sound should be a lovely boat ANYWHERE in the Texas bays. Aransas, Matagorda, Copano, Espritu Santo, Galveston, et al ( Galveston is actually multiple bays).

Put the sounder in if you wish- it's not a real requirement.

[JeffM]

Apteryx, I use the little portable LED nav lights from Duckworks.  I have the bracket for the combo light on the foredeck in front of the mast.  The stern light is on a pole I clamp to the corner of the cockpit edge (I don't have coaming there).  It is high up for visibility, but far enough forward not to foul the mizzen sheet.  The little bit of forward scatter turns out handy for reading the chart in the dark.

[paul_stewart]

It's great to hear all the above points and counter-points re sounder issues.  Thanks!  For several months I too have been trying to decide whether or not to have a sounder, and if so, which strategy.   (Even if "just for fun".) 

Graham,

   Pardon my ignorance but which 'Tom' would it be that installed the shoot-through transducer in the EC22 and would he like to share with us any tips (or lots and lots and lots of tips) about how to go about "grinding down the ply" without accidentally damaging the 6oz skin? 

Tom,

   Any comments?   

Wes,

  I hope you decide to go with a grind down to-but-not-through shoot-through installation so that you can try it first and let us know how it goes.  ;D.    Just kidding. 

     Better yet, some practice might be a good idea for anyone who decides to go that way:  take a piece of plywood and prepare it just as the target section of the hull was prepared with epoxy, glass, and even primer and paint on one side;  allow to cure/age enough;   then try the grinding process and see how it goes.  If the practice doesn't go well then back to the drawing board.   

     We do know something about the thickness of the hull.  So it should be possible to use/make some kind of "gentle" tool/jig that is set to grind down to only a target depth  --and no further!         

     Some miscellaneous experiences I had while building our CS20 lead me to believe that it might be possible to do it very slowly and carefully using small, sharp hand tools.  The inside of the glass skin is tough enough to tolerate some scrapping (but not puncturing) and the plywood could be picked away in small splinter.  Again, wondering what Tom would recommend.  Sounds like he took a "grinding" approach.

Ray makes a strong case (esp for those of us with slow reaction times)  for it not being necessary to shoot-through near the bow, although that may be one of the better locations for other reasons.   

How far from the centerboard must it be: if fore? if aft?   

New question:  What if you grind the inside to-but-not-through and install a shoot-through transducer and later that transducer goes bad?  That is,  the transducer fails but the display unit is fine.   Is that possible / probable?  If it happened, seems like it might be nearly impossible to neatly remove the dead transducer  ---because it is embedded in the hull within a bed of epoxy, right?    Perhaps you could simply disconnect it, leave it in place,  and install a new transducer near the one that failed.  Is that right?   

One more:  This is waaaaaaaaay out there, but....   a (transom mount) transducer might be of a size for temporary use hanging part way out the exit hole in the Anderson bailer (and blocking water flow in)  but the centerboard would have to be up.   Right?    Okay, you can stop laughing now.   Really.              Now would be good.       Any time now.

[Peter HK]

One more:  This is waaaaaaaaay out there, but....  a (transom mount) transducer might be of a size for temporary use hanging part way out the exit hole in the Anderson bailer (and blocking water flow in)  but the centerboard would have to be up.  Right?    Okay, you can stop laughing now.  Really.              Now would be good.      Any time now.

Stopped laughing...still chuckling though ;D

New question:  What if you grind the inside to-but-not-through and install a shoot-through transducer and later that transducer goes bad?  That is,  the transducer fails but the display unit is fine.  Is that possible / probable?  If it happened, seems like it might be nearly impossible to neatly remove the dead transducer  ---because it is embedded in the hull within a bed of epoxy, right?    Perhaps you could simply disconnect it, leave it in place,  and install a new transducer near the one that failed.  Is that right? 

That's what I found on a catamaran I used to own- an old dead transducer embedded in epoxy in one hull and a new one in the other hull. Here's a picture of the old girl- did some good cruising on her.

Peter HK