20 hour maint done lost a little top speed

[rnusr01]

Went from 45 down to 43 with same people etc. Used the Yamaha 5w30 synthetic oil and a new filter. Seems odd. Any thoughts?

Thanks

 

[JTaylor]

I assume you had comparable environmental conditions such as no big temperature swings or rougher water.  Do you keep your boat in the water or is it on a lift (or use a trailer)? I keep mine in the water and was amazed that I picked up 4.5 mph after spending 30 minutes cleaning the gunk off the tubes last week.  I find it odd that getting the oil and filter changed would cause a speed drop, although the gearheads on here would certainly know better. 

 

[rnusr01]

All the same makes no sense to me

 

[Rockie69]

Did you fill it up while it was out?

 

[rnusr01]

I warmed up he engine with a quick ride and then they put it on a trailer and did the service in my driveway. I always checked it before I went out and the oil levels were good

 

[SEMPERFI8387]

What about wind speed? Same speed in all directions? N/S/E/W ??

Also measuring via GPS or speedo?

 

[TomS]

Currents can affect this too, if in rivers. That's why speed records are done in 2-way fashion.

 

[rnusr01]

Using both speedo and GPS everything else seems the same with the exception of water temp it is up 3-4 degrees in temp from week before. It was 75 and now about 79

 

[Link]

How long between the 45mph and the 43mp?  My boat slows down throughout the year as the toons get dirty.  Try a good cleaning and see what hhappens

 

[kaydano]

I've noticed discrepancies between my phone GPS and my Garmin from our car. Not always, but I have seen them differ by up to 2 mph. So if you are using a phone gps, that might be the reason. One of your measurements may have been wrong. It's the only thing that makes sense to me. Changing your oil makes no sense. You'd have heard about that long before now (it would be a great marketing angle) if there was any basis for that.