Speedometer running slow

[johnennis]

2004 2120 with yamaha controls. It is reading about 1/2 of the speed my GPS is registering. The wheel seems to spin ok. Any ideas?

 

[Bryan 2530]

The Yammi speedo or your fish finder???

The yamaha speedometer works off water pressure on the front of the lower unit, probably got stuff in the hole there.

 

[johnennis]

Hmmm. I thought the speedo was the black plastic thing bolted to the stern with a little paddle wheel. Is that the sonar?

 

[Bryan 2530]

It probably is part of you fish finder but not knowing what your boat is equipped with it is hard to say.

Most in dash yamaha speedometer run off a pressure tube in the lower unit, yours may be different but I doubt it.

Pics would help.

What do you have for a fish finder? Does that show speed when underway?

 

[Megabyte]

The pitot tube that 'powers' the Yamaha speedometer is located here:

A 1/16" twist drill held in the fingers (NOT in a drill motor) can be used to clear most any clog that happens to close this hole.

 

[Bryan 2530]

Picture = 1000 words

 

[Megabyte]

Picture = 1000 words

Yep!

I took that photo this past fall when I changed the oil in my lower unit.
Since the speedo question is frequently asked, I took the photo to illustrate.

Finally got to use it!

 

[Bryan 2530]

I got in trouble on the Boston Whaler site the other day for posting pictures..... go figure. :?:

 

[Luv2fish]

Just had this happen this past weekend. Thanks for posting. It might be the answer to my problem.

 

[Megabyte]

bet ya those barnacle slowed you down a bit. need some anti fouling paint there on the bullet nose.
Better yet can you radie th eengine out of the water when it is tilted all the way up?

For whatever reason, the 'nose' doesn't come completely out of the water at full tilt, especially if I'm full of fuel. Once I'm lighter on fuel, she will come clear of the water. That's my 'fuel gage'.

But... that part of the LU did get a coat of paint this spring, so we'll see how it goes this season. :wink:

 

[johnennis]

It probably is part of you fish finder but not knowing what your boat is equipped with it is hard to say.

Most in dash yamaha speedometer run off a pressure tube in the lower unit, yours may be different but I doubt it.

Pics would help.

What do you have for a fish finder? Does that show speed when underway?

The fish finder is hooked into my Garmin 5212. The Garmin shows speed , which I thought was from the GPS. I'll operate the fish finder only to see, but what else would be the purpose of the paddel wheel.

Thanks to everyone for their responses.

 

[sparky]

It probably is part of you fish finder but not knowing what your boat is equipped with it is hard to say.

Most in dash yamaha speedometer run off a pressure tube in the lower unit, yours may be different but I doubt it.

Pics would help.

What do you have for a fish finder? Does that show speed when underway?

The fish finder is hooked into my Garmin 5212. The Garmin shows speed , which I thought was from the GPS. I'll operate the fish finder only to see, but what else would be the purpose of the paddel wheel.

Thanks to everyone for their responses.

Most GPS/Plotter/Sounders have SOG and speed.
SOG is calculated from the GPS position.
Speed is from the paddlewheel. I've found that the paddlewheels are troublesome, often getting tangled with marine debris, growth, or salt buildup. They are also prone to problems with installation location, including interference from a chine, strake, cavitation from the wheel, etc.

 

[johnennis]

In sonar mode no speed is indicated. Tried the 1/16" drill bit cleanout but still not working.