Please identify this sensor? Attached to my transom

[Old Ironmaker]

If a pitot tube faces aft how does it get the water in it? I know when I was taking flying lessons many moons ago the pre flight check included making sure the front facing pitot tubes were clean and clear of any obstructions.

 

[Silvertip]

The pitot does not face aft. It faces down and the hole near the bottom of the pitot faces FORWARD. It is also hinged so if it strikes something it will kick up (or at least it is supposed to).

 

[JimS123]

If a pitot tube faces aft how does it get the water in it? I know when I was taking flying lessons many moons ago the pre flight check included making sure the front facing pitot tubes were clean and clear of any obstructions.

If it faces aft then it pulls a vacuum and the gauge reads negative numbers.

 

[Old Ironmaker]

If it faces aft then it pulls a vacuum and the gauge reads negative numbers.

Thanks JimS123 . Do they face both ways? Aft and forwards? Now I'm second guessing myself if those Piper Cherokee 140's faced forwards.

 

[JimS123]

All boat pitots face forward and have a single hole. The instrument has a pin that the dial rests on, with the starting point usually at 5 or 10 mph. It takes that much pressure to get it started. If it were reversed, the pin won't move at all because the pin stops it.

Industrial pitots have the center hole as a boat, but also has holes on the side. It would be equipped with 2 tubes (hoses), one reads velocity and the other static pressure.

A third type pitot is the S-type. It has 2 tubes with holes facing forward and aft. It rewads velocity pressure (can convert to mph) and if that is turned around you get a negative number.

I have seen pitots on airplanes but never inspected one close up.

 

[Old Ironmaker]

I'll ask both my B-I-L's that both have planes where there's face. On their aircraft not boats, they have both and I'm jealous. One of them has a boat much longer than his plane. Grrrrrr. Lucky for me they are both good guys.

 

[Texasmark]

Ayuh,...... With air pressure,......

The water rarely gets more than a foot or so up the tube, unless ya unhook the other end,......
'n then it'll pee on yer legs,.....

On this note: Bought this 17 year old alum. boat. Taking it on it's first shake down cruise. Has the dash console and all the amenities and a shelf below. Was tooling along and felt water on my feet. Felt around (while driving) and the shelf was wet. Geez where did that come from. Felt around the general area and no source....like no hole in the hull type thing.

In short, the PO had the spedo-tube disconnected for some reason at the dash and the tube was peeing all over the place. So, it does pee on you if disconnected. Grin

Edit: Instruments are Farina. Just for grins had my Explorer GPS sitting next to me so I thought I'd check out the accuracy of the speedo since I was doing a prop slip calculation and had installed a new tach and seeing if things made sense. Mercury 115 hp so the engine had the pickup and the speedo was 17 years old. Dead-nuts on up to 38 mph.....end of the line. Impressed.