Knot Meter

[JBM]

Hi everyone. Although I have been reading this forum for a while now, I finally got registered and now I can post! You guys have already helped us quite a bit with the choice of an outboard (We'll be getting a Nissan 6), and a few other minor problems we have encountered with our Ariel, hull 318 (formerly Granny's Knot). This forum is great.

Here's the current problem: The knot meter doesn't work. I was told you could test the little thru-hull speed wheel with a volt meter. I don't seem to get any reading. The whole unit looks like vintage 1965 anyway so maybe it's time to replace. Has anyone done this? If so did you replace both the wheel and the guage? And where did you buy one?

Thanks in advance.

Jon

[Tony G]

Jon
It's always good to hear from another smitten individual:) I don't know anything about testing a speed transducer with a voltmeter. That, of course, doesn't mean it can't be done-just that I'm going to be no help at all there. I did take advantage of Navman's sale this last winter to purchase a 'speedo' and plan to install it this summer. 113 came with some sort of cable operated VDO knotmeter poking through the bilge and I quickley dispensed with that apparatus when we began stripping the boat. Being you allready have a hole in the hull, repacement should be pretty easy assuming (use word with caution) the transducer is in a good spot. There are so many options and models out there to choose from. One thing I noticed is some models are sold without transducers and some come as complete packages so make sure you're buying what you think you're buying. Also, if you think you might expand your instrument package down the road keep in mind that compontents can 'talk' to each other if they speak the same language to give you more info on what's going on.
Another option for a knotmeter is just using a GPS. I think every model now offers a speed over ground function (SOG) viewable in either miles per hour or knots per hour.
It'll be good to see what your question brings from this forum's members. The topic of depth meters, their transducers and locations has been covered before but I don't recall knotmeters being hashed out. Good luck with it and for crimony sakes, takes lots and lots of pictures. Tony G

[JBM]

Thanks, Tony for the quick reply. We do use a GPS on "Pearl" (hull 318) and will be getting a plotter this year I hope. I like knowing the water speed as well as the speed over ground. I wonder what knot meter the Ariels and Commanders came with originally. This one is a "Sumlog".

I'll do a little more ressearch on what's available and let you know. It looks like I'll have to go digital.

[John]

Valhalla came with a mechanical speedlog. It had a prop mounted on a small skeg which was under the aft port berth, which drove a display head through a speedometer cable, for those who remember such things. When VDO no longer had parts and the right angle gear went, I knew it was time.

I replaced it with a Standard/West Marine electrical speed log. It appears that the hole is about 2 -2 1/4"? I don't know if this is a standard size. I placed it in the forefoot because the old one would get airborne on port tack. This placement seems to have minimized but not cured the problem.

I ground out and filled the old hole with a combination of cloth and mat. I used 2 or 3 layers of mat in the middle to help make up the thickness. It still holds and I can't find the spot from the outside so I guess I did good work. I also filled the hole in the face of the cockpiut but that did not come out so pretty and is painted.

I hope this answers some of your questions and I am happy to answer any others if I can, or there are wiser <grayer??> heads here in the group

[John]

Jon,

Christmas Cove, ME?

[JBM]

Yeah, Christmas Cove, Maine is where we moor Pearl. It's a great little harbor at the end of a long penninsula in the heart of the mid coast region. Damariscotta river, Boothbay, Sheepscott river, Kennebec river and Casco bay to the west, Johns bay, Muscongus bay, and Penobscott bay to the east.

The only knot meter I have found so far has a transom mount transducer. I'd like to replace the little through hull wheel if possible. I'll check West Marine.

[John]

Jon,

My cousin has the old family cottage almost on Townsend Gut, across from Mouse in Boothbay. That's why I did a doubletake when I saw Christmas Cove. I grew up sailing all over from there.

As I said, I have a West Marine version of the Standard Horizon speedlog, and I have been very happy with it. You said you have a Sumlog. I think that is by VDO.

Try here: http://www2.vdo.com/vdo/end_consumer/ec_product&fza=&ID=922.aspx

The site lowtension.com show parts available for the mechanical one as well.

[JBM]

I just noticed - Manchester, Mass. I grew up in Marblehead, (but was a power boater back then).

[JBM]

The connection in the bilge seems to have been the problem. After some cleaning and WD-40 the knot meter is working. The VDO site helped, too. Glad I didn't need a new transducer - 178 English pounds.