I had a Norskog years and years ago that had a similar pickup, (well the pickup tube was identical, it was just hard mounted to the transom--bought many a pickup tube) anyway, Norskog told me that total topend would be effected 1/10th to 1 MPH. When GPS became affordable, I never really could tell much difference at 80mph, maybe a mile an hour? When I tore off the tube (again), I just used the GPS. They do make analog looking speedos that are GPS. I think on my next remodel that's what I'm going to do. I like the speedo sitting there, but I'm old school! haha!

That outdrive dragging in the water is slowing you down too, get rid of that BAHAHAHAHAHA

Yes, big time, but an arneson is not in my near future!

Speedo tube used to cost me 1 mph at 100.....bitd

I'm betting drive showers do the same...

Pilot tube never seemed to effet speed on my boats much if any. Drive showers seemed to though on several of the boats I installed them on.

A lot of the drive shower installs I see have the tube sticking down WAY further than it needs to be.

I actually did. 3mph. It had an adjustable pick-up. I did not notice it lowered itself and I spent a good amt of time trying to figure out what was causing the extra prop slip.

Finally noticed it while not looking at it specifically...LOL.

I had mine about 1/4" below the cav plate. Slowed me down ~2 mph. Cut the tubes to raise them 1/4" above the plate, and got the speed back. Video shows the shower works just fine at that setting.

Just read an old article out of hotboat magazine this morning while I was well you know...... They calculated the pressures on that kind of pitot tube at different speeds. Pressure was dramatic, 146 lbs. at 100mph, over 200lbs at 120 if I remember correctly. I'll take a shot and post it tonight. That will translate into some kind of significant speed decrease.