Going from Salt ot Fresh water, What happens to RPMs and Speed?

[Dinikin]

What have you noticed, assuming you can get your boat at WOT on flat water in both instances.
How much RPMs and speed diffirece is noticed?

[ICHTHYDEMON]

Never noticed anything.

[upperklam]

If there is any difference, it might be the altitude at sea level versus a freshwater lake at say 4000'. It's easier for humans to breathe at 500' than at 8000'. I think it's the same for motors, especially carbureted engines that can't automatically adjust to the altitude change.

[fish junky]

No change on my boat ether.

[backlash442]

Well with my old boat I noticed a rather large difference. It was a glass boat that weighed about 5000lbs wet. First time I put it in a lake I was surprised at how fast it trolled vs. the ocean. Couldn't keep it less than 3knts. Subsequent times I put it in the lake I noticed the same thing. Personally, I believe it's because there is no current/tide working against you. Plus saltwater has a different density.

Have yet to put my tin can in the ocean so can't say how that runs but maybe in the near future.

[baitsauce]

I've never noticed any difference except at high altitude like Odell or Wikiup.

I suppose it is in theory easier for a motor to push a boat in salt than in fresh because salt water is heavier therefore more dense, causing the boat to sit in the water higher and the prop being able to bite better. But other than the altitude thing I alluded to, I've never noticed any difference.

[Capt. Slick]

I have a 20' seahawk with a 140. the only difference I have found is do to with elevation. Wich at sea level and 4500' is about 1000 rpm and 8-10 mph.

[Jason S]

My boat is about 100 RPM's slower in a sea level lake in freshwater. This is for a 20' Seahawk with a Yami 150. Only reason I found it out was playing with prop's I propped it on a lake. Got the right prop to get it right around 6100 RPM with me in the boat and loaded like I will be for fishing. I can climb on the rev limiter in the Saltwater and not related to the current out there. The boat sits about 1" deeper in freshwater though. Salt will be slightly less dense.

This is my experience.

[Dinikin]

I been told that diffirence might be as much as 300RPMs due to the boat sitting higher in the salt, but just wanted to see what everyone else experienced.

[PRINCEMASTER]

If you have a boat with a deep draft there will be a difference just due to the difference in the density of the water. I may be wrong but it seems to me that salt water may take a little more effort to move through