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I've been running my triton using an scorpion outrunner 4020 1390kv, gets hot pretty quick and try to gets more runtime but in the end burnt the winding, that was on a fresh water pond. Then I try my other outrunner on salt water, longer runtime and motor just warm.
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Stiletto tunnel,EPV135 (53") twin cat, CT06"Spirit of Qatar", FD 47" mono, Twin Mini Cat 23.5" -
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Well nothuing is adding up for me... My runs were slower in fresh, looser, and cooler...? Ill run again in a few weeks to get better readings and two diferent mph readings, temps ecc... Then ill do the same in salt in the same conditions. But the water will be cooler in salt so temps will not be the same..Comment
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Guys,
this is just a thought, but maybee the salt is making the salt water more conductive, helping in the heat transfer process?
Dunno...???
Cheers...Tim.Comment
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I had a chance to give this some thought and think you are on the right track based on your saltwater harbor run and the freshwater run on my lake.
It appears that with the higher density of seawater the prop "digs" in more thus a higher speed by several percent. If this were the only factor we could easily confirm this by measuring the density of the seawater at Dana Point and comparing it to the fresh water in my lake. Density is easily calculated in you know temp and salinity. (http://www.csgnetwork.com/h2odenscalc.html
The Dana Point saltwater is at 60 F and 34 parts per thousand for salinity giving a density of 1.025106 (gm/cm3)
The fresh water in my lake has a temperature of 64F and salinity near 0 giving a density of 0.998666 (g/cm3)
This is a density difference of 2.56%, which potentially suggests that you would go 2.56% faster in seawater. We measured your speed consistent at 65 MPH at the lake, which, if our assumptions were correct, would be 2.56% x 65MPH or faster by 1.7 MPH in the Dana Point Seawater. This would put your Dana Point runs at 66.7 MPH and I believe this is close to what you have been recording. The math Gods have been good!
Now, in terms of the cooling there have been several views expressed in this thread. I tend to agree with yours and we can confirm that with my Eagle Tree logger. You say fresh water permits cooler running. I agree since fresh water has a higher specific heat (the amount of heat needed to raise the temperature of 1 kg or water by 1 degree C). The addition of salt reduces this heat storing capacity.
You posed some good questions but let me throw another in, air temperature. At the speeds these FE’s are running air drag becomes a major factor. Naturally you want to reduce the frontal area of the boat, make it streamline and have the lowest Cd, Coefficient of drag, possible. Cool air has higher density than warm air. Running in higher air temps would thus reduce air density and thus air drag also providing slightly higher speeds.
I’ll book us a trip to Dubai where the salinity of the Arabian Gulf is 30% higher than the open ocean due to evaporation and the air temps are well over 100! Those factors alone should see your boat clocking 70 MPH plus!Comment
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All I know is my real bassboat runs faster in cold water than warm.
I am sure it is running cooler at the motor as well and maybe the cool air intake is also adding to lower intake temps which increase power but Seems I am at the same RPM yet MPH is higher.
Hey....funny bit. My buddy has a new Champion 20' bassboat with a 225 Merc and he was fishing in the winter and was running down a cove and the motor suddenly kicked up so he pulled the kill swtch and his boat was sliding over ICE and sideways skiding until it slowed down and broke back through. Then he had to use his new FG hull to be an ice breaker until he got to the water again. Couple of chips in the nose V but nothing big. Hearing him tell it...well I was laughing so damn hard but just freeked the crap out of him. Well versed high speed driver too. He said all he could do is hold on to the side rails and take the ride.Comment
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[QUOTE=Jeff Wohlt;150090]All I know is my real bassboat runs faster in cold water than warm.
Colder water has a higher density and, if you go along with the higher the density the more prop dig theory, it would make sense. Your comments on running cooler are also quite valid. Loved the ice story!Comment
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I will say, the engine is just purring like a kitten when cold like that. Suckng down massive air with a Big Bore V-6 2 stroke with a big carb per cylinder.
After Bill Seebold Sr. worked on the prop for me the lift is crazy and top end is up 5-7 mph with the same prop. Probably the last prop he engraved his name on. He lived 1.5 hours from me and I went to his house. Should have seen the old mercs and racing outboard motors he had...I need to speak with Tim and see where it all ended up. Bill, jr...many time World champ boat racer only wants to play golf now.
The new outboards are now beginning to dominate motors around here in HP boats. 28' foot cats aournd here with twin 250 Mercs are running 115 mph down the lake with ease and 4 people in the boat.Comment
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what motor are you running on your boat Jeff? I acutally built a 30' Spectre Cat with a pair of 300 mercs for Mike Seabold a few years ago. I got to talk with him a few times as well as Bill when they came to the shop. I couldn't imagine the things they must have at their shop.Comment
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