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Catalina/Capri 25/250 Sailor's Forums

Catalina 250 Specific Forum

250 WB Thru-Hull

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SteveJK618
Deckhand

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6 Posts

Initially Posted - 06/18/2013 : 00:01:52

Sorry guys, if all this has been addressed elsewhere...

I plan to install a SINGLE thru-hull combined DST transducer in the usual place: square recess under the V-berth.

Can/should I mount it in the exact middle, i.e. on C/L--will the curvature of the stem and/or thickness of the hull here cause any issues with drilling, seating, sealing, etc.?

Or should I offset it a bit as if I were using separate D & ST transducers (which would also allow for a second thru-hull on the other side if ever needed)? If so, would I still use a zero-degree transducer (i.e. any deadrise concerns)?

Thanks!

"SKYBEACH"
2002 C250WB #618
Honda 9.9 LS
Vancouver, WA

The doomsayers will ruin everything!

Edited by - on

TakeFive
Master Marine Consultant

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2272 Posts

Response Posted - 06/18/2013 : 07:20:21

Before drilling that hole, at least look into doing the non through hull method using silicone oil or toilet ring wax. My boat came with a through hull, but if I had to install one I would be looking into it.

Use Google to find info on this.

Edited by - on

SteveJK618
Deckhand

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6 Posts

Response Posted - 06/18/2013 : 13:17:49

Thanks, Rick.

There is currently an in-hull Depth transducer puck installed in that area, but I'm looking to add Speed & Temp sensing, hence the DST thru-hull requirement.

The other option seems to be simply adding an ST transom-mount transducer, but I've heard from several experts it wouldn't work well on a sailboat. Anyone have experience with this on the 250WB? If so, where do you mount it?

Edited by - on

CJRoxs
Navigator

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USA
114 Posts

Response Posted - 06/18/2013 : 17:27:44

Comments from:

http://www.catalina-capri-25s.org/forum/topic.asp?whichpage=1& TOPIC_ID=26898#217544

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> I will be doing the one that doesn't require cutting a hole in the hull. I will loose the temp gauge but I plan on putting a wheel sensor that has the temp gauge in it, on the stern sometime in the future.

Also, I used vaseline in place of other liquids on my other boat. It works great and less chance of a splash/spill. It also holds the transducer in position.

I never thought about using the wax but I can see that melting that into the PVC containment pipe would do the same as the vaseline.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Edited by - on

bear
Admiral

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USA
909 Posts

Response Posted - 06/18/2013 : 18:55:06

Installed Garmin fish finder through hull under V berth 5 years ago with toilet bowl wax. Has temp readout, depth and relative picture of any fish and contour of lake bottom. Never a problem, however you must have a good 12 volts available to run unit. Never cared how fast I am going. Safety and comfort more important than how fast. JMTCW

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CJRoxs
Navigator

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USA
114 Posts

Response Posted - 06/18/2013 : 23:05:31

By through hull you mean shoot through the hull, not cutting/drilling through the hull? If that's true and the temp sensor works that's a big plus.

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Ape-X
Admiral

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USA
662 Posts

Response Posted - 06/19/2013 : 03:49:32

I've been told by not drilling and simply sounding through the hull, that temperature is off by only a few degrees. If you are not a oceanographer, then that should be plenty accurate

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bear
Admiral

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USA
909 Posts

Response Posted - 06/19/2013 : 04:14:40

I have found my thru hull temp sensor to be also affected by hull temp, but not much difference.

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SteveJK618
Deckhand

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6 Posts

Response Posted - 06/30/2013 : 22:09:22

The transducer manufacturers use the term "in-hull" for devices that sense through the hull without drilling a hole, which is what I currently have.

"Thru-hull" is used for devices installed in holes that penetrate the hull, i.e. it refers to the installation, not the operation of the transducer. A bit confusing, I'd agree.

It's apparently possible to sense speed through the hull by pinging bubbles, for example, but this seems less reliable than a mechanical paddlewheel, and definitely more high tech (i.e. expensive).

I don't care so much about temp sensing, but I do want a readout of boat speed through the water, since I sail in a constant river current. I've found that GPS speed (SOG) alone won't tell me how my boat is performing nor, more importantly, how much current I'm fighting at any given time/point on the river.

Thus, since I keep hearing a transom sensor won't work well on a sailboat, I'm forced to seriously consider the thru-hull option.

Which brings me back to my original questions: Anyone have experience with either a drilled thru-hull installation OR a transom-mounted paddlewheel?

Thanks, Steve

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 07/01/2013 : 01:59:44

We have the Raymarine ST40 Tri-Data system on our C250WB.

It has dual transduces, both are 'Thru-Hull' ie. 2 holes in the boat!

'Our' transducers have a fixed cable length, not sure about DST's, the guy that installed them ran the wires aft down the stbd side and then across to the port side which left them not a lot of slack. Were I to install them today I would run the cable down the stbd side.

We have wheel steering and the display is at the helm.

The transducers are on either side of the centerline which is pretty flat.

I would shoot for putting it on the side rather than the center. Really makes no difference that it is 4" off center in that area.

Paul

Edited by - on

SteveJK618
Deckhand

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6 Posts

Response Posted - 07/01/2013 : 11:20:34

Thanks, Paul; great info and just what I needed!

I'm looking at the Raymarine i70 display and AirMar DST800 smart triducer.

I don't have a steering wheel, so will probably mount the display on the exterior bulkhead next to the companionway. I'm also considering an interior "swingarm" mount, but it's a pricey option.

I think the DST800 has a 3m cable, which may not be long enough to reach the display by itself. The approved solution is to buy a SeaTalkNG starter kit, which links display, sensor, and power via a 5-way "backbone" connector. Then the "spur" cable adds the needed length to reach the instrument.

The minimalist in me wants to plug the power and transducer cables directly into the back of the display, but it's not clear that would work. The connectors look like they'd fit, and I can't see how the instrument would know the difference, but I've tried w/o success to confirm this with Raymarine tech support (both via phone and the online forum)--they seem uncomfortable with such an "unorthodox" proposal. So I guess I'll just have to try it and see for myself! (If only to satisfy my curiosity.)

It's good to know the sensors can be mounted off center. I think the "0-degree" version can tolerate up to 22 degrees of deadrise, which sounds like more than enough from what you describe. I was concerned that the curvature of the stem might make it more difficult to seat & seal the transducer if it had to be mounted on C/L.

Can you confirm it's just 3/4" of solid fiberglass I have to bore through in the transducer alcove? No core, air gaps, or water tanks?

Thanks again, Steve

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 07/01/2013 : 13:01:58

Bear in mind that we have a WK, so stick with Paul's or another WB owner's recommendations. Here's a photo that might help, showing our transducer & speed log forward of the keel. They're the two big blue dots forward of the keel kinda right of center, and for perspective, they're about a foot apart or so, and about a foot+ forward of the keel. Inside the boat they're less than a foot forward of the water tank, but I don't know if our tank sits in the same place as a WB tank. It's not the greatest photo, but gives you an idea of placement.

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SteveJK618
Deckhand

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6 Posts

Response Posted - 07/01/2013 : 22:02:54

Thanks, David. That is helpful.

I assume the shape of the WK and WB hulls is the same, so it looks like it's relatively flat where I'll mount the sensor--didn't take a good look at that before I dropped it in the water this season. Looks like offsetting won't create any angle issues for the depth beam.

OTOH, seems I might even be able to mount on C/L if the curvature in that area is as uniform as it appears. While offsetting in case I later need another thru-hull seems prudent, I wonder if this ever results in asymmetrical speed readings on opposite tacks when heeled over? Is the sensor on the windward side ever exposed under typical sailing conditions? The yard drilling the hole speculated this could happen.

Thanks, Steve

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