Core Sound 20 Hull #102

[Designer]

Paul,

Tom Lathrop was the perpetrator. He definitely ground the plywood away. Fortunately you can grind the veneers away one at a time. If you had a trim router you might be able to find a place where you could use the router set to just less than the thickness of the ply and rout down to the glass. I think that he probably used epoxy to bond the transducer but If you were concerned about removal, you could set it in silicone caulk which is not as tough as epoxy. Because the transducer is plastic and if it is dead you could always grind it away. Transducers rarely quit, I believe that they can lose some sensitivity over time but we are more interested in shallow depths.

The other reason That I put mine forward is that it is under the bunk and out of the way.

If anyone is looking at a depth finder they should look for dual frequency so that it will be more sensitive in shallow water.

[Charlie Jones]

Most definitely on the dual freq. We have a single freq finder and it goes nutso in less than 4 feet, which is when you need it the most.

Gonna swap it out for something else soon

[wkisting]

Not sure if this is right, but the folks at West Marine tell me that any transducer will have trouble reading properly, if at all, in less than 4 feet of water because the signal returns back to the sounder too quickly, causing it confusion because it cannot process that quickly. They told me the dual frequency only makes a difference in extremely deep water (deeper than 60 feet), when the other frequency (50Mhz, I think) returns a better signal from deep bottoms; otherwise, the 200Mhz is best for general purpose and what most fisherman use. This seems to agree with what I've read online also.

Still, if you permanently mount one, it's probably wise to get the dual frequency.

I'm toying with the idea of mounting my skimmer in line with the keel. The skimmer has a little "arm" on it for mounting, and if I rout a small hole in the aft edge of the keel for that arm, I can install the skimmer there, just barely above the bottom plane of the keel, right in front of the rudder blade (but not touching it). Still not sure I want to do that, but it seems like an ideal location for a good signal and constant submersion.

[Apteryx]

Raymarine's ST40 is rated for zero to 400 feet, so it would be a good backup for the centerboard. If the foredeck crew was untrustworthy with regard to centerboard soundings, the quarterdeck could double check with the electronic sounder, cutting back on grog as the two systems fell into disagreement. 

The transducer bolts into a bung, so it's replaceable without surgery.  I think it seals to the bung with O-rings but I'm not sure.  I have that transducer on my catboat and it's been quite nice and reads any bottom right up to to the point I'm aground.  I check it routinely but it's never leaked a drop.

Kind of expensive at $250 or so but I'm tempted.  The unit I've got also has a knotmeter transducer, which is good for evaluating sail trim.  It's better than a GPS for that because it reacts immediately but I think I'll pass on the CS17.  If the waterwheel transducer can get banged by trailer bunks it would break.  Or, if it gets crunched down on rocks or oyster shells it would be gone.

In other words, I think the knotmeter would be a liability.  Depth, I'm still tempted.

[Charlie Jones]

Two problems Ray-

First one is that the sounder is in our 25 foot sloop with the 2500 pound fixed cast iron keel. The transducer is two feet below the water line so when it's reading 4 we're really in 6. I need a little more than that. The one we had in the previous boat would happily read down to 2 feet . Which in this boat would be 4 feet of water, and would suit us fine, since we draw 3'3"

Currently, when we are in iffy water, Laura is running the boat and I'm on the bow with the lead line- it ALWAYS reads true

Second problem is that the OTHER boat has a dagger board ;D

[wkisting]

I agree on the shallow water remarks, Ray--the CB offers plenty of warning for that.

I'm keen on the depthfinder for other reasons: For anchoring purposes, and because I like to see what's under the water before my wife and I dive in to do swimming, etc. Also, I think it could be handy for navigation if matched with a chart that has depth soundings, and it definitely comes in handy for fishing--which we also plan to do from our CS.

I'm not installing it for shallow water warning purposes... indeed, as I said before, the West Marine folks told us to count on it NOT working very well in less than 4-6 feet of water. In any case, the water on our lake here in GA is clear enough that you can SEE the bottom down to about 6-10 feet, so I don't really care about sonar in that case.

If I only had a GPS unit, I wouldn't bother installing a separate sonar unit. But since my wife bought me the fancy combo unit, I might as well install it... I do think it will be handy for anchoring and fishing, and there were times on our last boat (especially on the muddy Mississippi) when I would've LOVED to have sonar.

[Ken_Potts]

   Ray - Do you find the new digital charts more useful than the analog style?

[Ken_Potts]

  I like to have a chart too.  My gps doesn't tell me everything I need to know.  It's also an old gps that doesn't have pictures and it's been behaving erratically lately so if I'm getting out of sight of the ramp it's not a bad idea to have a paper back-up.  I'm too good at getting lost.

[lbrewer]

If one were to carefully grind/rout/gingerly scoop out an area of the plywood to the exterior glass layer, I think I would be more comfortable filling the newly made void with epoxy, then glassing over on the inside and mounting the transducer in bedding compound over the newly created solid spot.  I like the idea of that spot being sandwiched with glass.  If the transducer failed, you could remove it from the bedding compound.

Larry

[wkisting]

Agreed. On a lake, I may only use a GPS. But on the ocean or any unfamiliar body of water, I would not recommend relying on GPS alone. Electronics can fail or misread, and it's never wise to depend on them by venturing into unknown waters without a chart (and the ability to read it). Down here, the lake is large enough (72,000 acres) that I'll keep a paper map on hand.

[Charlie Jones]

Aboard the big boat we have two GPS units, both loaded with the exact same waypoints and routes, all with the same names. Laura sets those up using Chart Navigator ( or SeaClear- I can never remember which)

We also have all charts needed for where ever, loaded onto the laptop.

Additionally we have a printed out version or a purchased paper chart for the whole trip. With the experimental NOAA "print-it-yourself" charts, anyone can have all the paper charts they need. We just printed the latest version of the chart for our home bay ( Matagorda) and put that into a notebook.

On the Texas 200 we had a GPS and paper charts aboard for the whole way, and for the side bays too.

[Dale Niemann]

I like Ray's ideas.  Use the centerboard and leadline. 

DON'T FORGET THE KISS principle.

Dale

[wkisting]

Well, I think we're having two separate discussions... certainly one can do without a GPS for navigation, and without Sonar for shallow-water maneuvering. In those cases a map, CB, and leadline will suffice. And I think the KISS principle is generally wise and appealing. Of course, even by KISS reasoning, a GPS/Sonar might qualify to some as a form of added simplicity, not complication (with the exception of the initial installation hassles and having to maintain the battery).

The primary reason I want GPS on my CS is because I find the speed readings and plotted trajectories invaluable for learning to sail better. I used a simple black and white handheld unit on our last boat, and its data helped me teach myself to sail much better with regard to tweaking sail shape, tacking angles, etc., as well as being able to calculate distance/mileage much more quickly than working with a paper chart. I would just keep using that handheld unit, but my wife gave me this new color GPS/sonar combo unit (Lowrance LMS-520C) as a birthday gift, and it will be very nice to have mounted on our CS.

I want to hook up the sonar chiefly for anchoring reasons (which a leadline can assist with, but not as instantly or easily), for fishing (not something a leadline can help with), and for identifying obstructions under the water before diving in to swim with friends (again, not something a leadline can help with--at least not practically).

[wkisting]

I made a mahogany bowsprit to hold my anchor on the bow in an anchor roller (for easy deployment), to protect the area around the forward mast hole from scuffs from stepping the mast, and also to help deflect deck water away from the forward mast tube. I'm thinking it would be wise to bolt it on with a good sealant instead of permanently gluing it to the deck, no? I've never carried my anchor on the bow before, but I suspect it may scuff the wood and eventually lead the bowsprit to need replacement. Do most of you agree? Or is it better to glue bond it?

I would think that three or four 1/4" bolts bolting it through the kingplank (plus the #10 fasteners holding on the forward cleat I'm installing) would hold it down securely enough to handle any anchoring stresses in rough water. No?

[Apteryx]

Wes, got any pictures of that bowsprit?  Also, what are you doing with the rode, do you have a hawsepipe?

That makes for a convenient way to store an anchor, but feeding the rode back down a hawsehole kind of puts a lot of bottom crud in your chain locker.  No big deal if it's drained and easy to clean.  maybe an arrangement like Southern Skimmer's chain locker would be the way to go.

[wkisting]

Well, we decided to skip the anchor locker and hawse pipe for exactly the reasons you mentioned. There's so much room in the cockpit at the forward seat, so we decided to just store our rode in a square plastic milk crate, which will drain and clean easily and also allow the rode to dry out without rot/mildew problems. But we do want to store the anchor on the bow, I think, so that it can be easily deployed from the cockpit when/if I sail alone. It's not critical, just a nice feature to have. I'll still have to go forward to cleat the line off, but the anchor will be able to set and secure the boat first, which will be handy.

I'll snap a pic of the bowsprit when I get a chance. It's nothing too fancy, just a 28-30" long board that protrudes about 6" past the bow. The rest runs back to the forward mast hole and surrounds it to deflect deck water away. I tapered the forward edge and the aft edge a bit to make it look a bit nicer and more "finished" than a simple, flat plank. It also visually balances the look of the boat because I needed some mahogany up front to counterbalance (aesthetically, not by weight) the mahogany tiller.

[wkisting]

Snapped some pics quickly...

To compensate for the deck curvature, I cut a very shallow "V" in the underside of the sprit, running lengthwise. Seems to make for a nice fit that will seal easily with bedding compound.

Not sure if I like this or not. I tried a few different shapes and liked this style the best. What do you guys think?

Another possibility would be to stop it before it reaches the mast hole and then taper the width (not thickness) of the board so that it narrows as it runs aft. That might make for a nicer shape, but I would lose the benefit of water being deflected away from the mast hole, which is why I chose this shape.

I believe there is about 5" - 6" of overhang at the bow, which is just enough to let the Danforth-style anchor hang there with a little gap to prevent the flukes from touching/marring the bow paint. My regular duty anchor will be the 4lb. Fortress anchor (model FX-7) which many folks use as a lunch hook. I'll carry a larger anchor in the cockpit for more critical anchoring situations, but I expect the Fortress will be more than adequate for 90% of my anchoring, so I built it to accommodate that anchor.

[Edit to add: I found that I could cut the overhang down by a few inches once I attached the bow roller, which overhangs the wood sprit. I like the looks better after cutting it down.]

[JeffM]

I may go to a milk crate myself--its nice to have a clean deck, but I'm tired of hanging upside down in the forepeak after every trip and sponging up the seawater that came in on the rode.

[Charlie Jones]

On Pilgrim I sized the opening so Travis could fit a five gallon plastic bucket in there. The deck pipe opens directly over that bucket so all slop goes there, rather than into the boat itself.

I did fillet and tape all the edges in the anchor rode locker so it would be easy to wash and wipe down, but he usually doesn't need to do so.

Also lets him keep other odds and ends up there that won't get hurt getting damp.

[JeffM]

Wes, the mainmast drain works famously, so you needn't worry about spray or whatnot getting in the step.  I've never touched mine, except to squirt a little water into it when it occurs to me, to make sure nothing is clogging it.  But it always runs freely.

On the subject of anchors, my Danforth-style dragged twice in Cuttyhunk Pond a week ago.  Fortunately the trolling motor was already rigged and I was able to get out of shoal water and try to re-anchor both times.  The anchor had held all night, but dragged when the wind rose in the morning.  (I've learned to mark the anchor position on gps just as I drop, then I get it to read distance from that point to so I'll know it it has grabbed, and if it lets go.)  Does anyone have a favorite anchor for bottoms a Danforth doesn't like?  There don't seem to be many other options in the low-cost category.