Your cruising speed?
- Thread starter Roy & Dixie
- Start date
lloyds":1v321b3q said:
I'm with you on that. I like the slow cruise, but I generally do it with both 40's down and running. I have, on occasion, shut one down and pulled it up out of the water, if I am in very shallow water. In those cases, I am usually observing the bottom out the window, and have someone on the other side doing the same.
I like having both engines available for a dozen good reasons, but the baot just feels right with them both down and running.
Harvey
SleepyC :moon
I agree, that control of the boat with twins, even with an auto pilot can be a pain at displacement speed with only one motor down, so unless it's completely calm, I run with both motors down with only one running & the one that's not in neutral. With the down motor spinning freely in neutral there is only enough drag to reduce the milage by about one to two tenths of a mpg. The increased rudder effect of both motors down to me feels very near having them both running. Of course when exploring in tidal zones or other poorly charted or uncharted waters at times we will be running with one motor completely up & the one running only down far enough to maintain cooling water.
On a long stretch of more open water where wildlife viewing is minimal there are times I would prefer to be cruising at about 12 to 15 mph but hold at displacement speed for the advantage of increased fuel range & cost saving, which can be considerable when on an extended all summer cruise in areas where fuel prices are very high. On our cruises in 2003 & 2004 most all or at least 90% was done on plane & now since retired it's just the opposite with the 90% being at displacement speed, especially in Southeast Alaska where the beauty & wildlife viewing is pretty much a constant, leaving no reason to rush to any particular place except perhaps for weather & tide windows. The other exception being sea conditions. At times it's just best to set the speed for what ever makes the ride the most comfortable & safe.
Jay
On a long stretch of more open water where wildlife viewing is minimal there are times I would prefer to be cruising at about 12 to 15 mph but hold at displacement speed for the advantage of increased fuel range & cost saving, which can be considerable when on an extended all summer cruise in areas where fuel prices are very high. On our cruises in 2003 & 2004 most all or at least 90% was done on plane & now since retired it's just the opposite with the 90% being at displacement speed, especially in Southeast Alaska where the beauty & wildlife viewing is pretty much a constant, leaving no reason to rush to any particular place except perhaps for weather & tide windows. The other exception being sea conditions. At times it's just best to set the speed for what ever makes the ride the most comfortable & safe.
Jay
Bob,
I'm running 11 1/8 x 13 props. I recall hitting 28 mph racing to catch a lock on the Mississippi a few years ago. Can't say the prm's. We generally run in a much more relaxed fashion.
I hope to get to Weffings in Feb for some motor work I hope they can help with the props. I've had excellent service from them, especially Alan. It's a shame I have to go almost 1000 miles for good service. I have a decent Honda shop about 70 miles from here, but it's a great reason to visit Appalachicola.
What props are you other brats with twin 40's running?
Bruce
Carpy
I'm running 11 1/8 x 13 props. I recall hitting 28 mph racing to catch a lock on the Mississippi a few years ago. Can't say the prm's. We generally run in a much more relaxed fashion.
I hope to get to Weffings in Feb for some motor work I hope they can help with the props. I've had excellent service from them, especially Alan. It's a shame I have to go almost 1000 miles for good service. I have a decent Honda shop about 70 miles from here, but it's a great reason to visit Appalachicola.
What props are you other brats with twin 40's running?
Bruce
Carpy
Bruce, with our either cruising very heavy on extended cruises at sea level or somewhat lighter when closer to home at a very high altitude we've settled into a constant use of 12 inch x 10 pitch three blade Solas Stainless for our Honda 40's. Rpm's & max speed varies with the altitude, boat weight, wind & tide, but on average max is about 20 mph at 5600 rpm & a speed of about 15 mph at 4600 rpm
Jay
Jay
That is interesting in regards to the control with only one motor in the water. We almost always only have one motor down and never have a control issue - autopilot seems to run normal. I wonder if it has anything to do with the Perma-trim's that we have installed??
I do put down both engines while docking, but only to have a bit more trust at the last minute if needed (but only use the Port engine control - easiest to move).
I do put down both engines while docking, but only to have a bit more trust at the last minute if needed (but only use the Port engine control - easiest to move).
We too have Permatrims & they, I believe do give increased steering control along with their other benefits. It's not that the boat cannot be controlled with just one motor down & quite well in smooth water, but with increased wind & waves the auto pilot or person steering must put in more effort to maintain a straight & smooth heading & as conditions deteriorate, I tend to go from the one motor down & other up to both down & one not running to in somewhat rougher seas both engines down & running for the best control. Robert, could it be you only prefer to use the one engine displacement speed cruising when sea conditions are good & if not go to both engines down & running & have not been in a sea state where the additional rudder while only running the one motor would have made the noticeable difference many of us have experienced with twins on the CD22. To me having both lower units in the water gives a very noticeable improvement in steering control over only the one & hard for me to fathom otherwise.
Can't say I remember running with both down and one running, at least for any length. If I shut one down, I will usually raise it. Control (steering) just seems slower. I have never had the auto pilot running when I am just using a single OB down.
This has me wondering. Do you mind elaborating?
Was it really "trust", or a typo for Thrust? Might change the meaning.
Harvey
SleepyC:moon
This has me wondering. Do you mind elaborating?
Was it really "trust", or a typo for Thrust? Might change the meaning.
Harvey
SleepyC:moon
Hunkydory":3hybmjie said:
Hi Jay,
Yes, that could be - when the sea state is "more than enough" (one time going across Death's Door on the Great Lakes), then I would normally have two engines down and running thru the "valleys" as much as possible. But in comfortable wavy situations, I'll still run only with one down. Guess I've never been in the situation yet where I put two down to get better control - usually just put two down to increase the thrust (or to go fast).
We always run on autopilot with one down, so maybe the autopilot is working harder than I realize.
FYI: We just watched a couple of your YouTube videos the other night - great videos!
1) Twin engines, both down, one running, one stopped.
2) Twin engines, one down running, one up stopped.
My Honda manual says set up 1) can cause "reverse flow"
of water in the engine down and stopped resulting in
engine damage.
2) is recommended in the manual for twin engine set ups
with only one engine running.
Comments?
Aye.
2) Twin engines, one down running, one up stopped.
My Honda manual says set up 1) can cause "reverse flow"
of water in the engine down and stopped resulting in
engine damage.
2) is recommended in the manual for twin engine set ups
with only one engine running.
Comments?
Aye.
Foggy,
I'm away from home so can't access my Honda manual now, But I have talked to the head mechanic at Bridge Bay Marina on Yellowstone Lake where they have 20 some of the Honda 40 hp motors in operation during the summer months & I questioned him about the leaving one motor down not running. He told me as long as It remained in neutral no engine or lower unit damage would result. Now with several thousand miles of operating this way, I would say what he said has proved to be true. Perhaps with the higher hp Honda motors damage could result.
Jay
I'm away from home so can't access my Honda manual now, But I have talked to the head mechanic at Bridge Bay Marina on Yellowstone Lake where they have 20 some of the Honda 40 hp motors in operation during the summer months & I questioned him about the leaving one motor down not running. He told me as long as It remained in neutral no engine or lower unit damage would result. Now with several thousand miles of operating this way, I would say what he said has proved to be true. Perhaps with the higher hp Honda motors damage could result.
Jay
Hi Foggy,
Some questions as a result of your 1) & 2) scenarios:
For an engine down, but not running, is it in neutral and rotating or in gear and not rotating? If rotating, is the lower unit adequately lubricated rotating in reverse? IIRC. drag on a twirling prop is the same as a disc of the same diameter.
Since twins are not parallel with one another, and the lower HP engines are not counter-rotating, I would think that asymmetric disc (P-factor) and prop walk effects would be different on each side, compounded by how far engines are from the centre line, so that 1) & 2) would have a favoured side, that would provide better tracking and steering control than the other side. I wonder if it is enough to worry about, except maybe on a TomCat?
All this boat thinking is so entertaining on a closed-in winter day
.
Rod
Some questions as a result of your 1) & 2) scenarios:
For an engine down, but not running, is it in neutral and rotating or in gear and not rotating? If rotating, is the lower unit adequately lubricated rotating in reverse? IIRC. drag on a twirling prop is the same as a disc of the same diameter.
Since twins are not parallel with one another, and the lower HP engines are not counter-rotating, I would think that asymmetric disc (P-factor) and prop walk effects would be different on each side, compounded by how far engines are from the centre line, so that 1) & 2) would have a favoured side, that would provide better tracking and steering control than the other side. I wonder if it is enough to worry about, except maybe on a TomCat?
All this boat thinking is so entertaining on a closed-in winter day
.Rod
FYI: We just watched a couple of your YouTube videos the other night - great videos![/quote]
Robert, I was pleased to see you thought the videos worth watching & glad to you did. I actually enjoy watching them on You Tube at times too. It's much easier & less time consuming for me to watch the short video clips then watch the hours I have of them on the big screen TV, but they sure look better with true HD on a big screen tv.
Jay
Robert, I was pleased to see you thought the videos worth watching & glad to you did. I actually enjoy watching them on You Tube at times too. It's much easier & less time consuming for me to watch the short video clips then watch the hours I have of them on the big screen TV, but they sure look better with true HD on a big screen tv.
Jay
Since lower units all operate in an oil bath, lubrication will be the same if the prop is rotating with the shifter in neutral and passively turning or the engine is in gear, and the motor is turning the shaft. With inboard engines, it is an entirely different story, and they need the oil to be circulating.
Since when prop is in gear, it should not turn due to engine compression. It the prop turned, and thus the engine turned, there could be some damage. It would take a lot of force to turn the engine, with a prop in gear.
Since when prop is in gear, it should not turn due to engine compression. It the prop turned, and thus the engine turned, there could be some damage. It would take a lot of force to turn the engine, with a prop in gear.
It seems to me, rather than incoming lower unit water pressure turning the
prop which turns over the engine or vane damage in the water pump, the
damage comes from the "reverse flow" of water entering where it shouldn't be
via the exhaust/cooling system which is not pressurized with a stopped engine.
Apparently, this can happen (only ?) with a stopped engine, gearshift in reverse,
and the boat moving forward.
I wonder if this "reverse flow", with unwanted sequela, can also happen docked,
moored or anchored in a current if your engine(s) happen to be put into reverse
while stopped?
From the BF90D Owners Manual:
and
Curiously, the manual has no recommendations for flushing with fresh water by
using ear muffs over the lower unit water intake ports (which I thought was
routine); only using a garden-hose-to-flush-port-connection located on the
side of the engine without the motor running for 10 minutes while in the down
position.
Curious indeed.
Aye.
prop which turns over the engine or vane damage in the water pump, the
damage comes from the "reverse flow" of water entering where it shouldn't be
via the exhaust/cooling system which is not pressurized with a stopped engine.
Apparently, this can happen (only ?) with a stopped engine, gearshift in reverse,
and the boat moving forward.
I wonder if this "reverse flow", with unwanted sequela, can also happen docked,
moored or anchored in a current if your engine(s) happen to be put into reverse
while stopped?
From the BF90D Owners Manual:
and
Curiously, the manual has no recommendations for flushing with fresh water by
using ear muffs over the lower unit water intake ports (which I thought was
routine); only using a garden-hose-to-flush-port-connection located on the
side of the engine without the motor running for 10 minutes while in the down
position.
Curious indeed.
Aye.