speedo

[4.0l sahara]

I use my boat on a large lake. The lake has alot of weeds and the pressure tube speedo always gets clogged and is not accurate. I also have a paddle wheel for my fish finder witch I believe to be pretty accurate. If I switched the pressure tube to the fitting on the outboard for my speed would that be more accurate? Also how accurate are paddle wheels? I can't remember if I checked it with the gps.

 

[ziggy]

Re: speedo

if ya got a gps, neither of the other speedo are gonna be in the contest for acuraccy....

 

[Silvertip]

Re: speedo

There are a couple of things that affect the accuracy of a pitot speedometer. Accuracy of the head itself, and the accuracy of the pitot. As for the pitot, it doesn't matter if its the plastic style hanging down off the back of the boat or the one on the engine. If the head is inaccurate, speed is inaccurate. If either of the pitots are inaccurate, the head can be accurate and the speed will still be wrong. The pitot must face forward regardless where its at so either one is likely to plug. The paddle wheel will be more accurate at slower speeds than the pitot. But as was mentioned, GPS is the only way to know exactly how fast you are going.

 

[Mkos1980]

Re: speedo

GPS is the only way to know exactly how fast you are going.

Ditto. I do have to admit though that the best reading I got was 55.1 on my boat and with GPS the old VDO Gauge was dead on 55 also LOL. How often does that happen lol.

 

[4.0l sahara]

Re: speedo

With the padle wheel it said my max speed was 68mph. I thought that I checked it with the gps but can't remember. It looked like I was doing 70 by comparing it to cars I could see that I was flying by.

 

[John_S]

Re: speedo

Both paddle and tube type are effected by current as well. Paddle wheels are more accurate than tubes at slow trolling speeds. Not sure about paddle wheel, but tube type generally get more inaccurate at higher speeds.

If you have GPS, yep as accurate as you are going to get. If you can only borrow a handheld, you can "map" your existing instruments. By watching/comparing rpms and speed, you can tell if you are having a problem or not.

All that said, you may snag less weeds/debris using the engine tube vs seperate tube or wheel. Worth a try.

 

[amynbill]

Re: speedo

Whew...was afraid this thread was about the etiquette for wearing a speedo.