Slow water?

Great Video, that guy is nuts, barefooting when you know there may be ice chunks in the water.   My buddy hit a 2' long 2x4 when we were barefooting near dusk.
His foot was messed up. I bet an ice cube could do the same.
Pretty cool to watch, the people on shore looked amazed also.

I will try that, thank for the tip!

gun-driver wrote: https://www.youtube.com/watch?v=7_F0fy1XyoE +1 Best of both worlds

https://www.youtube.com/watch?v=7_F0fy1XyoE

Best of both worlds

8122pbrainard wrote: Gary, In the dead of winter up here, people do some weird things to keep themselves busy!

I like that Pete,is that a recent photo ?    - American ingenuity at it's finest,one registration, all year use

Here'as a link to what may or may not be the real or semi real story back in 2005

link

Have to be pretty board to actually go out cut a hole and launch the boat into it. Hold my beer and watch this. I like parking in the shade and looking at ice in my glass

Well, they sawed a hole in the ice the size of the hull. Brought the boat out on the ice on the trailer. Slid the boat off the trailer into the open water and then paced some loose snow in around the gaps between the hull and the ice. All for the photo shoot.

Gary S wrote: Don't be getting gundriver all excited- he'll be cutting off the top off his boat and mounting it on his sled

Man, I want to know more about that pic.

Your right men, sketchy data!

But I can't let gp its not the first time I've noticed drop in top speed this time of year, my 41 mph boat would turn into 39 when I take it out for the year, then turns back into 41 mph the next season, no mods.

Maybe the calculus says just get the 541.

Slow water.............here's slow water



But anyways, after reading Tom's story I decided to take a boat ride today and see what my results would be.

Kinda like Tom's conditions air temp was probably mid sixties and the water had cooled off from a max of about 82 in late summer to 56 today.

We'll call the boat "old scuzzy bottom". it was cleaned about a month ago and scuzzed up a bit since then

Knowing what it has for a top speed, I checked it again today (and a lot of other days under various conditions) and it was basically the same as when the water was in the 80's. with about the same amount of scuzziness on the bottom. It lives in the water for 5 to 6 months of the year with a bottom cleaning every now and then

So Tom, I think there's something "not right" with the boat/engine

3 mph and a few hundred RPM loss sounds a lot like secondaries that aren't opening just as a first guess

Just think how much of a dog it would be in 40 degree water if the viscosity had that much of an effect

Wishful thinking, perhaps?

How many data points do you have to characterize the engine/boats performance? If minimal, do you have reason to believe that the previous points were achieved in optimal conditions (or borderline unbelievable)? 300rpm is a lot of RPM to lose- I can’t say I’ve ever seen that much variation due to conditions. 3mph, yes. All bodies of water act a little different but more often than not my boats run faster when it’s cooler out.

huh.
Air temps were summery yesterday afternoon , nothing that would alter the underhood temperature. Engine temp normal 165, thermostatically controlled
Little more fuel than usual and a cold water, thats about it

Hydro resistance issue aside, engines will run better or worse depending on temp and humidity. Generally colder, dryer air will increase performance because of the denser air charge.   Thus most would likely experience a perceivable increase in performance after a marked drop in temperature. That being said, if the norm is a 10-15% relative humidity and it jumps to 80-90% you won't see that increase, and possibly even a decrease, even if the temps are lower. But honestly, the kind of temp difference that make performance physically noticeable is probably much greater than what you've experienced thus far anyway.
Further, there are studies showing the correlation between charge air temperatures and performance. It was suggested (and some say proven) that the key is really the DIFFERENCE in cylinder temperature and charge temperature that determines the relative boost you may have in relation to temperature changes. As such if the engine is up to running temps but the cooling system is helping to provide a cooler cylinder temperature as well as cooler external air temps (less excessive humidity) a marked increase in combustion rate would follow.   
I'm thinking if you are feeling a decrease in performance it's either due to a much higher humidity than you normally experience or there is another issue causing it. I can't speak to the hydro-dynamics here ... perhaps there's a hydro engineer in the forum?

I seem to recall my boat running faster in the cold.