Question for people with "fast trawlers"

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What percent of the time are you at Hull speed?

  • 80%+

    Votes: 22 40.0%

  • 70%

    Votes: 6 10.9%

  • 60%

    Votes: 2 3.6%

  • 50%

    Votes: 4 7.3%

  • 40%

    Votes: 3 5.5%

  • 30% and under

    Votes: 18 32.7%
  • Total voters
    55
No chance of surfing them when anchored or in a confined passage.
 
Simi60,
Didn't think of an anchored boat w others blasting by. They deserve the whipping post! I don't think I've ever seen that. Scratch my plans to immigrate to Oz.
 
Simi 60 said:
I have no issue with speed, in the right hull.
We had a 60 ft power cat go past a few days ago doing 20+ and almost zero wash. Marvelous display of efficient design.
Should be more of it.
Click to expand...

One of our more bizarre boating experiences occurred last year when proceeding down a narrow channel near a Navy special operations base. We looked and saw a boat coming down the channel at very high speed. As it got closer it looked like someone had turned a F117 stealth fighter into a boat. I told my wife to prepare to be waked.

This boat, maybe 30 feet long, passed us doing at least 60 knots and the sailors aboard waved as they went by. Leaving absolutely no wake. Nothing. :ermm:

Later, I asked someone who had some knowledge of these boats from having helped build them, and he said they were designed to leave no wake, because there was no point in having a stealthy boat, if radar could pick up its wake and know it was coming, and that they were basically skimming along on an air cushion.

I don't know how long it will be before we see these at the Miami Boat Show, though.
 
It all depends on where we are going and why. Overall speed was the greatest discussion that my wife and I had when buying the boat. We knew we wanted to go slow but with work deadlines and family commitments we had to have the option to go fast if needed.

This Saturday we will head out on out annual 16 day trip with the boat. The current plan is to run hull speed for all of the legs but 2. The trip from Boca Grande to Key West and from Key West to the Dry Tortugas will be run at 16-17kts. This will shorten our long crossing by about 7.5 hours and the trip to the Tortugas will allow us more time there.

Obviously time is not the only trade off. At hull speed we burn around 6 gph with the genny running. Running fast we are at around 23gph.
 
k9medic said:
It all depends on where we are going and why. Overall speed was the greatest discussion that my wife and I had when buying the boat. We knew we wanted to go slow but with work deadlines and family commitments we had to have the option to go fast if needed.

This Saturday we will head out on out annual 16 day trip with the boat. The current plan is to run hull speed for all of the legs but 2. The trip from Boca Grande to Key West and from Key West to the Dry Tortugas will be run at 16-17kts. This will shorten our long crossing by about 7.5 hours and the trip to the Tortugas will allow us more time there.

Obviously time is not the only trade off. At hull speed we burn around 6 gph with the genny running. Running fast we are at around 23gph.
Click to expand...

I always wonder why leave a gen set running constantly while motoring along? Batt bank can be charged by engine alternator and inverters can run most items. Is gen set running to power AC's??
 
Art said:
I always wonder why leave a gen set running constantly while motoring along? Batt bank can be charged by engine alternator and inverters can run most items. Is gen set running to power AC's??
Click to expand...

AC's, Freezers, Dishwasher, Washer, Dryer, Hot Water Heater, Watermaker, Kitchen Appliances.
 
Group9 said:
One of our more bizarre boating experiences occurred last year when proceeding down a narrow channel near a Navy special operations base. We looked and saw a boat coming down the channel at very high speed. As it got closer it looked like someone had turned a F117 stealth fighter into a boat. I told my wife to prepare to be waked.

This boat, maybe 30 feet long, passed us doing at least 60 knots and the sailors aboard waved as they went by. Leaving absolutely no wake. Nothing. :ermm:

Later, I asked someone who had some knowledge of these boats from having helped build them, and he said they were designed to leave no wake, because there was no point in having a stealthy boat, if radar could pick up its wake and know it was coming, and that they were basically skimming along on an air cushion.

I don't know how long it will be before we see these at the Miami Boat Show, though.
Click to expand...

I've always dreamed of boats floating on air cushion for speed and other items. Can you find out what gph, i.e. nmpg, that stealth boat accomplishes? - Thanks, Art :popcorn:
 
Art said:
I've always dreamed of boats floating on air cushion for speed and other items. Can you find out what gph, i.e. nmpg, that stealth boat accomplishes? - Thanks, Art :popcorn:
Click to expand...

I'm not sure these boats even officially exist! :D
 
My boat is set up with The refrigerator, freezer, and air-conditioners on an AC buss.

If I want my refrigerator and freezer to run the generator has to be on.

I've done the math and the cost to put an inverter in with additional batteries would be around $3000. With the current diesel prices I can run my generator for about 1500 hrs. before that would break even.
 
k9medic said:
My boat is set up with The refrigerator, freezer, and air-conditioners on an AC buss.



If I want my refrigerator and freezer to run the generator has to be on.



I've done the math and the cost to put an inverter in with additional batteries would be around $3000. With the current diesel prices I can run my generator for about 1500 hrs. before that would break even.
Click to expand...


Have you factored in the amortized cost of the wear and maintenance on the genset? I have no idea just curious. Of course, it may be that you will end up selling the boat long before the genset needs to be replaced.
 
Originally Posted by Simi 60 View Post

"I have no issue with speed, in the right hull.
We had a 60 ft power cat go past a few days ago doing 20+ and almost zero wash. Marvelous display of efficient design.
Should be more of it."

I designed and built a 28' OB that was (hydraulically) a trimaran of very light displacement. Since there were three hulls it left three little rooster tails and they made two more between them and slightly aft. So I always had five little roostertails following the boat.
Since the boat was ultra light disp and had easy lines she left very little wake.
With a monohull easy lines, light and narrow is the formula for low wakes.

But making a small wake is hardly the aim of most boat buyers. Indirectly though as any disturbance of the water needs to be paid for with fuel burn.
 
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dhays said:
Have you factored in the amortized cost of the wear and maintenance on the genset? I have no idea just curious. Of course, it may be that you will end up selling the boat long before the genset needs to be replaced.
Click to expand...

I tried to as best as possible. I change the oil out every year and with a gallon of oil costing around $19 and a filter of six dollars I just can't get the math to add up.

Even if I did a direct operating cost analysis I just don't see that it would be much of an improvement for me.
 
I run my Mainship 34 at 15-16 when on a longer cruise, usually when the Admiral is aboard. But if there is nowhere special to go, we also enjoy 7-8 knots. But this lower speed is only around 30% of the time.
 
I have put about 800 mile on my boat this summer. Probably 100 miles at around 7 knots, about 600 miles at 9 knots and the final 100 miles at 10 to 11 knots. I can make 15 + at wot but eat fuel like a wide body 747. Boat and I are both happy at 9kn.
 
bayview said:
all too often hull speed is used as a synonym for cruising speed or an efficient speed. It is neither. This very poll implies it is a desirable speed. My answer to the poll was never but that was not an option.
Flank speed of carriers has nothing to do with what we discuss here other than as an example of maximum speed increased with length and unlimited budgets.

As a replacement with a more descriptive term for efficient cruising I suggest, for your next target of attack, bow down speed.
Click to expand...

One knot below hull speed works for me which provides about 100 percent efficiency (less than half the fuel cost per mile).
 
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Interesting guestion and difficult to answer. My boat will go over 20 knts but we usually run at 17 knts to get to our destination if possible. Since we love the Bahamas we get there fast (17 knts) and then travel about 6 knts. So distance wise we probably go more mikes at speed but time wise we probably go more miles at a slow speed. I really don't enjoy traveling over the ocean or the banks of the Bahamas at 6 knts, too many hours of boring scenery of just water. ?
 
Bigsfish said:
Interesting guestion and difficult to answer. My boat will go over 20 knts but we usually run at 17 knts to get to our destination if possible. Since we love the Bahamas we get there fast (17 knts) and then travel about 6 knts. So distance wise we probably go more mikes at speed but time wise we probably go more miles at a slow speed. I really don't enjoy traveling over the ocean or the banks of the Bahamas at 6 knts, too many hours of boring scenery of just water. ��
Click to expand...

On a cruise ship, I prefer at-sea days rather than at-port. Must partially explain why I prefer open-sea travel on a relatively-stable ship rather than a "bouncing" small boat as well as resting/playing while the professionals drive the boat.
 
Last edited:
Bigsfish said:
Interesting guestion and difficult to answer. My boat will go over 20 knts but we usually run at 17 knts to get to our destination if possible. Since we love the Bahamas we get there fast (17 knts) and then travel about 6 knts. So distance wise we probably go more mikes at speed but time wise we probably go more miles at a slow speed. I really don't enjoy traveling over the ocean or the banks of the Bahamas at 6 knts, too many hours of boring scenery of just water. ��
Click to expand...

Those speed figures, and time doing so, are basically what we do too... although not in the same location at all.

For another item: We also [occasionally] cruise on one engine at 4.5 to 5 knots in confined locations with 5 mph speed limits and anchored, moored, docked boats in the area. This slow speed gives us nearly 3 nmpg. At just a little over a gallon per hour a period of time slowly moving forward is pretty inexpensive. By working it with tide-currents 7 +/- nmph otg can be achieved.
 
It's a shame some boats can't maintain a speed under five knots with all engines at idle. Such boats require playing with the transmission or cutting out an engine. :whistling:
 
Mark

I find under 5 knts is not conducive to easy steering.
 
Bigsfish said:
Mark

I find under 5 knts is not conducive to easy steering.
Click to expand...

Seems like you need more effective rudders if transiting a marina or no-wake zones.
 
Mark

We don't even have rudders, we have pod. :)
 
I have no problem with rudder steering while moving forward at any speed. When I cut engine speed all the way down to to 600 rpm low idle... that is mostly to do close position maneuvers such as docking. At that rpm throttles and trany shift levers are pretty much all I use with rudders left straight.
 
Approaching berth/dock, I'm usually drifting in neutral expecting an approach speed of under one knot. Engaging idle-speed for turning, or in reverse to check speed. Idle speed of 750 RPM results in 3 knots, while five smph ("no wake" speed) is achieved at 1100.
 
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