posted 07-18-2001 03:22 AM ET (US)            

I'll be the contrary one here and encourage you to install the speedometer. I like them because they are simple, reliable, inexpensive and can be accurate. Even if they are not accurate, they are precise. I mean that literally; they give the same readings over and over, so while they cannot easily be calibrated, you can learn what the real speed is by comparing the readings to a more reliable source like a GPS and remembering that it, for example, over registers by 2 mph @ cruise speed.

To install, use a hole saw to cut the hole. If you use a drill motor it had best be a 1/2" motor and preferably an angle drill like a Milwaukee "Hole Hawg". A 3 3/8" hole saw requires a lot of torque and a little 3/8" home owners drill won't cut it, so to speak. Better yet, remove the piece to be drilled and use a drill press. Much safer for you and the wood. A hand held drill motor and hole saw can twist your wrist good and "walk" out of the pilot hole and just chew the hell out of you freshly varnished mahogany. I don't mean to scare you, just be careful.

Once the gauge is mounted in the console you simply plug the speedometer hose (pressure, not vacuum from the pitot tube activates the gauge) into the back of the gauge. There is no wiring unless you want to install an instrument light which comes on with the nav lights so you can read it at night.

Mount the pitot tube on the transom and run the hose up and over the transom to the speedometer itself. Very simple.

I've always hated paddle wheel speedometers because they are notoriously inaccurate. They always seem to over register quite a bit (like 15-20%). The ones I've owned did not have any calibration feature. That sounds like the solution to that problem right there.

The other down sides to a paddle wheel speedometer are that they require electrical wiring, cost more money, and if you hit some debris and the paddle wheel itself is damaged it will cost a lot more than replacing a pitot which costs less than $10 and which for the most part won't need replacing anyway because it will simply kick up if it hits something like a log or if the boat is pulled up on the beach. Like I said, pitot speedometer very simple, very reliable.

posted 07-18-2001 08:36 AM ET (US)            

On one of my Yamaha 70-HP outboards there is a hose coming out of the lower unit, and I assume this is for a speedometer connection. Is this commonplace on ouboards?

I don't see where the PITOT opening is located on the lower unit, but it must be somewhere! Any hints?

posted 07-18-2001 08:41 AM ET (US)            

I located one at a power tool specialty store. It was a MILWAUKEE brand.

posted 07-18-2001 09:18 AM ET (US)         

It common for there to be a speedo pickup on outboards. All 3 of the Mercuries that I have owned had had this.

gnrgunner,

I would add my voice to those advocating you forgo the speedometer. By the time you pay for the speedo and the tools to put one in you could get a GPS. If you want a fishfinder you could get a speedo pickup on that as well. Tom w. clark is very much correct in stating that the Teleflex speedo is very reproducable. But then so are GPS and Fishinder speed readings. Plus, the Teleflex model you are thinking of getting will be useless at speeds under 5 MPH. Speed readouts on Fishfinders can be very accurate, my Garmin 240 reads within 1/2 mph of a GPS, from idle to WOT; without any adjustments.

Personnaly, I think you would be much better off with a tach and a GPS and/or speedo equipped fish finder.

posted 07-18-2001 11:29 AM ET (US)            

Well, it was a great idea that didn't work too well for two reasons. First and foremost, the gear case location meant the if you hit a piece of driftwood or whatever, bits of it would be rammed into the pitot opening. A conventional pitot tube simply flips up out of the way. My gearcase opening suffered this plugging never to be freed again, oh well. The other problem was the plastic barbed fitting on top of the gearcase was very easily broken off. This happened to me as well. I reverted back to a conventional pitot tube and OMC stopped building producing the gearcase mounted pitot, I assume, for the above reasons. Perhaps others have done it better....

Getting back to drilling the hole, I agree that if you don't own the tools and buy them it will cost some $. You could rent them, but borrowing them is even better. Whether gnrgunner should or should not install this speedometer needn't be dependent upon the drilling of the hole. I don't think it's a big deal but then again I have a whole shop full of tools and a set of hole saws. A 3 3/8" size is not hard to find though. Most hardware stores should stock them.

There is nothing wrong with having an analog speedometer in addition to a fishfinder with a paddlewheel speed sensor and a GPS. In fact I think this is the preferred route. I have had all these on a couple of my boats, though I have now stopped paying the extra 50 or 60 bucks for the optional speed/temp sensors because of their inaccuracy. But like I said earlier, if they can be calibrated (can the temp be calibrated too?) then I might reconsider.

posted 07-22-2001 10:59 PM ET (US)            

AS far as installation - the bigest pain for me was getting the darn steering wheel off. There are no holes for a standard Wheel puller and the legs of the gear puller I had were too short... Tried all kinds of things chain, nylon webbing etc to give the puller something to hook to. Finally gave up and used a hammer. Worked. Just use a center punch on the bolt and give it a bunch of solid bumps while pulling back on the wheel.
(loosen the nut on the inside of the console a little to give the wheel more play.

As far as wiring - The speedo is just a tube like others said. The light is electrical but simple. Run a line to your negative buss and a hot wire to a switch on the panel. You'll want the light to be controlled by a switch. If you have a lighted tach, you can just use a jumper from the speedo like you would on a house switch when carrying the circuit on. Use 16guage Anchor wire. The tach has the circuit for the light, a wire to the ignition switch, and a wire to the sender from the motor. Sender is Gray for Johnson.

Cutting the holes is really no big deal. I purchased a 3 1/2 in hole saw at Home Depot - $12.00, already had the arbor but its only like $9 more if you need it. Mark your hole. Keep a firm grip on the drill and go slow till its in about a 1/4 inch then speed up. I cut through 1/2 inch mahogony and 3/4 inch plywood + the fiberglass with a cheap black and decker drill. If you take the wheel off, you probably won't need an angle drill. IF you have a handle that will screw into the side of your drill, use it to help control the drill against the torqe.