I Just Don't Get it...

ITD · 08-27-2011, 03:35 PM

Hmmm, I don't think that water travels that fast but it really doesn't matter.

When you are in moving water your boat becomes part of that moving mass. If your engine is off you will move with the water, as fast as the water is moving for all practical purposes. With the prop engaged at idle your boat moves the same speed relative to the water whether the water is still or moving. If your boat steers in still water at idle speed, it will steer in moving water at idle speed. This is true whether you go with the current or against the current. The only difference you will notice is your speed relative to land or stationary objects. If you are going with the current you will be moving faster than your idle speed relative to land, if you are against the current you will be moving slower relative to land.

The fastest point in that water is maybe 4 or 5 mph when the dam is wide open, at least from what I have seen. My boat will travel about 6 or 7 mph at idle. If I use the lower speeds for my example, my boat will travel at 2 mph relative to land going toward Meredith bay. Traveling toward Paugus bay, my boat would be traveling at 10 mph relative to land. Either direction, as far as the boat is concerned, it is going thru the water at 6 or 7 mph.

Let say the water is going 9 mph in my example. Then at idle speed, my boat would still steer fine going with or against the water, the only problem is that I would be going BACKWARDS relative to land at 3 mph if I travel against the current. In that case I would have to speed up my boat, but I have never seen the channel flowing that fast.

Pulling out from Thurston's heading toward the Weirs can present some problems if you are not careful, but that is another matter.

NHskier · 08-27-2011, 03:57 PM

We slip our boat at Thurston's and went out yesterday afternoon. According to my chart plotter, our normal headway speed through the channel, when the dam is closed down, is about 4.8 mph. Yesterday it was reading about 2.4 mph as we went under the bridge.

And yes, a wide-open dam makes for some real challenges there, both coming and going!

lak · 08-27-2011, 05:32 PM

Without doing any math or scientific analysis...

I usually go through the channel comfortably at about 800 RPM to maintain no wake.

Went through about 1:30 AM on Friday night/Saturday morning and was at about 1400 RPM just to get 2.4 knots (about 2.75 MPH). I've never seen the current flowing like it was last night.

ishoot308 · 08-27-2011, 08:27 PM

Quote:

Originally Posted by lak

Without doing any math or scientific analysis...

I usually go through the channel comfortably at about 800 RPM to maintain no wake.

Went through about 1:30 AM on Friday night/Saturday morning and was at about 1400 RPM just to get 2.4 knots (about 2.75 MPH). I've never seen the current flowing like it was last night.

That pretty much duplicates my experience as I normally go through at around 1000 RPM and today I needed around 1600, exactly the same difference in RPM as you.

I too have never seen the channel flowing as fast as today.

Dan

08-27-2011, 03:57 PM	#2
NHskier Senior Member Join Date: Aug 2006 Posts: 298 Thanks: 45 Thanked 37 Times in 34 Posts	We slip our boat at Thurston's and went out yesterday afternoon. According to my chart plotter, our normal headway speed through the channel, when the dam is closed down, is about 4.8 mph. Yesterday it was reading about 2.4 mph as we went under the bridge. And yes, a wide-open dam makes for some real challenges there, both coming and going! __________________ NHskier

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08-27-2011, 03:35 PM	#1
ITD Senior Member Join Date: Apr 2004 Location: Moultonboro, NH Posts: 2,953 Thanks: 484 Thanked 703 Times in 393 Posts	Hmmm, I don't think that water travels that fast but it really doesn't matter. When you are in moving water your boat becomes part of that moving mass. If your engine is off you will move with the water, as fast as the water is moving for all practical purposes. With the prop engaged at idle your boat moves the same speed relative to the water whether the water is still or moving. If your boat steers in still water at idle speed, it will steer in moving water at idle speed. This is true whether you go with the current or against the current. The only difference you will notice is your speed relative to land or stationary objects. If you are going with the current you will be moving faster than your idle speed relative to land, if you are against the current you will be moving slower relative to land. The fastest point in that water is maybe 4 or 5 mph when the dam is wide open, at least from what I have seen. My boat will travel about 6 or 7 mph at idle. If I use the lower speeds for my example, my boat will travel at 2 mph relative to land going toward Meredith bay. Traveling toward Paugus bay, my boat would be traveling at 10 mph relative to land. Either direction, as far as the boat is concerned, it is going thru the water at 6 or 7 mph. Let say the water is going 9 mph in my example. Then at idle speed, my boat would still steer fine going with or against the water, the only problem is that I would be going BACKWARDS relative to land at 3 mph if I travel against the current. In that case I would have to speed up my boat, but I have never seen the channel flowing that fast. Pulling out from Thurston's heading toward the Weirs can present some problems if you are not careful, but that is another matter.

08-27-2011, 05:32 PM	#3
lak Junior Member Join Date: Jun 2010 Posts: 8 Thanks: 0 Thanked 1 Time in 1 Post	Without doing any math or scientific analysis... I usually go through the channel comfortably at about 800 RPM to maintain no wake. Went through about 1:30 AM on Friday night/Saturday morning and was at about 1400 RPM just to get 2.4 knots (about 2.75 MPH). I've never seen the current flowing like it was last night.