I want a fuel-sipping cuddy!!

[UncleWillie]

Re: I want a fuel-sipping cuddy!!

Mine's got 6'3" of headroom...

Well then, that begs the question of just what is a Cuddy?
It seems you can call anything a Cuddy if want to.

A Cabin Cruiser is what the Modest Captain calls a Cuddy Cabin?
And a Cuddy is what the 90 foot Yacht owner calls anything with less than three staterooms?

I aways thought a Cuddy had low headroom an no permanent amenities.
Now I am hearing folks with 6"3" headroom, Stove, Sink, Fridge, and Permanent Head calling it a Cuddy!

 

[sam60]

Re: I want a fuel-sipping cuddy!!

Our 25' Cabin has the enclosed head/shower, galley with stove & fridge, aft cabin and only has 5'-8" of headroom...it must be a cuddy...

 

[Mischief Managed]

Re: I want a fuel-sipping cuddy!!

Well then, that begs the question of just what is a Cuddy?
It seems you can call anything a Cuddy if want to.

A Cabin Cruiser is what the Modest Captain calls a Cuddy Cabin?
And a Cuddy is what the 90 foot Yacht owner calls anything with less than three staterooms?

I aways thought a Cuddy had low headroom an no permanent amenities.
Now I am hearing folks with 6"3" headroom, Stove, Sink, Fridge, and Permanent Head calling it a Cuddy!

I rely on the manufacturer to label it. Regal calls my boat a cuddy, so I do the same. I do not think it's a cabin cruiser.

my boat:

A 25 foot Regal cabin cruiser:

The cruiser is clearly a lot taller. I prefer the sleeker look of mine.

 

[Scott Danforth]

Re: I want a fuel-sipping cuddy!!

if you want fuel economy in a boat that has a place to sleep, and a place to crap, the boat will have a sail on it.

if you want to go 50mph at cruise, your talking something that will go WOT at 65+, you can forget economy, speed costs

if you want to take a 200 mile trip in a boat, use the average cruise speed of 15 mph. I routinely run 85 to 100 miles when boating the bay of green bay. its an all-day affair with a boatload of fuel being spent.

 

[cyclops2]

Re: I want a fuel-sipping cuddy!!

Open bow
Cuddy
Cabin

There is not another type

 

[UncleWillie]

Re: I want a fuel-sipping cuddy!!

Open Bow, Cuddy, Cabin...There is not another type

Closed Bow Runabout, Without Cabin?

 

[UncleWillie]

Re: I want a fuel-sipping cuddy!!

I rely on the manufacturer to label it. Regal calls my boat a cuddy, so I do the same. I do not think it's a cabin cruiser...I prefer the sleeker look of mine.

Would it be safe to assume the cabin does NOT have room to stand upright for the average adult?

P.S. I like it Too!

 

[04fxdwgi]

Re: I want a fuel-sipping cuddy!!

What lake in NH? We boat on Winnipesaukee all the time. I intend to take mine on the Hudson eventually.

Mine likes 32 MPH for fuel consumption, but the stepped hull seems happiest above 40 MPH. I'd like to increase the power enough to have a 40 MPH cruising speed at 3200 RPM. Thinking procharger... Not really concerned with top speed. I suspect the MPG at 40 MPH would be close to what it is now at 32 MPH, if the engine RPM could be lower.

My boat is 2550 as well, but it's a Regal. It has about 500 hours on the 7.4 MPI

Boat on Sunapee

About the pro charger... You may be a tad disappointed in the results you are looking for. Requires "X" number of HP to push a boat thru the water at a given speed. Those HP convert directly to BTU, thru the burning of fuel, and are somewhat proportional. The charger helps by increasing compression, or boost, creating the HP at a lower RPM. The fly in the ointment here is that as the air is increased, so is the fuel needed for the correct ratio to sustain optimal ignition. You can increase HP at a lower RPM, but that is useless unless you want greater accelleration or you change gears and / or size / pitch of prop to attain a higher speed at a given engine RPM, afforded by the increase in HP. But know you have to "work" the engine harder to spin the new setup at a slower speed to push a boat further per rev of the prop. Again, HP / BTU is figured in, to push hull at a given speed, just at a lower RPM, but similar HP/BTU, but at a lower RPM. See where this is going?

There the rub lies, you still need "X" number of HP to drive thru the water at a given speed. This is a constant due to hull design. The BTU needed by engine combustion to create "X" HP remains fairly constant. The charger changes all this by manipulating the efficiency of the combustion, but is a trade off in the increased power at a RPM. By increasing your cruise speed from 32 to 40, you have also increased the HP/BTU required to propel boat at the increased speed by a rather large amount, meaning more fuel.

Sooooo, you may see an increase in your fuel consumption at one point and a decrease at another. There are so many variables involved here that it would entail a basic redesign of the entire engine / drive power plant for a given hull design and that, my friend, is a HUGE expense. Your dream of increasing from 32 to 40 on same fuel consumption may be just that, a dream.

Like it has been said "You don't get nothin for free."

 

[Mischief Managed]

Re: I want a fuel-sipping cuddy!!

Boat on Sunapee

About the pro charger... You may be a tad disappointed in the results you are looking for. Requires "X" number of HP to push a boat thru the water at a given speed. Those HP convert directly to BTU, thru the burning of fuel, and are somewhat proportional. The charger helps by increasing compression, or boost, creating the HP at a lower RPM. The fly in the ointment here is that as the air is increased, so is the fuel needed for the correct ratio to sustain optimal ignition. You can increase HP at a lower RPM, but that is useless unless you want greater accelleration or you change gears and / or size / pitch of prop to attain a higher speed at a given engine RPM, afforded by the increase in HP. But know you have to "work" the engine harder to spin the new setup at a slower speed to push a boat further per rev of the prop. Again, HP / BTU is figured in, to push hull at a given speed, just at a lower RPM, but similar HP/BTU, but at a lower RPM. See where this is going?

There the rub lies, you still need "X" number of HP to drive thru the water at a given speed. This is a constant due to hull design. The BTU needed by engine combustion to create "X" HP remains fairly constant. The charger changes all this by manipulating the efficiency of the combustion, but is a trade off in the increased power at a RPM. By increasing your cruise speed from 32 to 40, you have also increased the HP/BTU required to propel boat at the increased speed by a rather large amount, meaning more fuel.

Sooooo, you may see an increase in your fuel consumption at one point and a decrease at another. There are so many variables involved here that it would entail a basic redesign of the entire engine / drive power plant for a given hull design and that, my friend, is a HUGE expense. Your dream of increasing from 32 to 40 on same fuel consumption may be just that, a dream.

Like it has been said "You don't get nothin for free."

My boat has stepped-hull and a pad keel and that seems to add a wrinkle to the efficiency equation. The running angle changes substantially between 32 and 40+. The bow drops and the boat runs flatter, even with added trim. At 40 it feels like it's fully "on the step". At 32, it does not. The speed increases more per RPM above 32 than it does below 32. I know drag is a function of the square of speed, but the equation is not perfect, you can see that on any planing hull when you plot fuel efficiency at planing speed vs plowing speed. I think the stepped hull adds a secondary bump in the fuel use curve further up in the speed scale. However, the RPM required to reach 32 MPH seems to be the sweet spot for the engine. It also happens to be at the engine's peak volumetric efficiency RPM, so pumping losses are minimized there. I think you'll find most marine engines have the best power/fuel consumption somewhere near 3000 RPM.

I can go 40 MPH and not suffer much of a MPG drop right now, and I suspect much of the drop is due solely friction losses within the engine and drive and that the hull is not suffering a typical increase in drag as speeds go up (I think drag per MPH is increasing, just not at the same rate as a no-stepped/non-pad keel hull. Those engine losses increase with the square of RPM on any engine, so anything that can be done to reduce RPM while keeping power output the same will have a noticeable effect on efficiency.

I'd be OK with the same efficiency as I'm getting now at 40 MPH with a procharger, if I could get the RPMs down. I just love the way the boat feels at 40. It's much more lively and responsive than it is at lower speeds. I hate winding the motor up to 3800 RPM all the time though, just seems like a bad idea...

 

[Mischief Managed]

Re: I want a fuel-sipping cuddy!!

Would it be safe to assume the cabin does NOT have room to stand upright for the average adult?

P.S. I like it Too!

It does have the headroom for anyone under 6'3" to stand up, but only in a small area in the cabin. The sole area with said headroom is only about 3 square feet. The hull has 24 degrees of deadrise, draws a ot of water and has a sharp entry. This allows for a deep sole in the idle of the cuddy cabin. The sole is higher further forward under the table. You can see the deep well here:

 

[Sunsetrider]

Re: I want a fuel-sipping cuddy!!

If I can stand in it (5-8) I can sleep in it!

 

[bekosh]

Re: I want a fuel-sipping cuddy!!

If you are planning on boating on big waters, then you also need to look at how the boat handles the chop. That means you want a deep V hull with a good amount of deadrise. You are also looking at some longer range cruising and that means a big fuel tank.

The 1991 Wellcraft Eclipse 216XL like I used to have seems like it would come close to fitting the bill. They are a 50mph boat with a SB V8 and even with a 7.4l big block we averaged 2.5mpg over the time we owned her. They have a 52 gallon fuel tank for a range of 100+ miles and a 20? deadrise that gives a decent ride through choppy waters.

My wife and I slept aboard about 20 times per summer and with a full canvas enclosure there is enough room for 2 people to be reasonably comfortable.

But you do look a little out of place when you dock at a marina on the big waters. :facepalm:

 

[NSBCraig]

Re: I want a fuel-sipping cuddy!!

Look for a hull with a pad not a deep v. (22 Velocity would be a nice choice).

Also consider an outboard too. saving weight always helps economy.

 

[ssobol]

Re: I want a fuel-sipping cuddy!!

... I know drag is a function of the square of speed, but the equation is not perfect, you can see that on any planing hull when you plot fuel efficiency at planing speed vs plowing speed. ....

Your assumption on drag is correct if things remain constant. However, unless you have a full displacement hull, increasing the speed of a semi-displacement or planing hull significantly changes the shape and size of the hull seen by the water. You are changing the hull shape in real-time. Generally speaking the portion of the hull in the water will get smaller and the fineness ratio will increase. Both will increase the speed that the boat can move through the water for a given horsepower. The added hull pressure on the water will reduce the gain in speed a little as the induced drag will increase as the effective hull area gets smaller. The hydrodynamic force per unit area has to increase to keep counter the weight of the boat (which has not changed). The effective shape of a displacement hull also changes with speed as seen by the water, but not anywhere as much as a planing hull.

For a typical day use boat starting from a stop and advancing the throttle slowly you will see at first a fairly linear correlation between fuel burn and mph as speed is increased. As the speed increases further and the hull starts to rise, the fuel burn (rpm) will go up substantially, but the speed increase will be less (the boat is essentially moving up hill as it climbs out of the water). Once the bow wave is crested the boat starts planing and the speed will increase rapidly. Once the boat planes, you are back to a fairly linear correlation between fuel consumption and boat speed. A plot of fuel flow versus speed will show a peak or break in the curve somewhere around the middle when the boat starts moving from displacement to planing mode.

 

[Mischief Managed]

Re: I want a fuel-sipping cuddy!!

Your assumption on drag is correct if things remain constant. However, unless you have a full displacement hull, increasing the speed of a semi-displacement or planing hull significantly changes the shape and size of the hull seen by the water. You are changing the hull shape in real-time. Generally speaking the portion of the hull in the water will get smaller and the fineness ratio will increase. Both will increase the speed that the boat can move through the water for a given horsepower. The added hull pressure on the water will reduce the gain in speed a little as the induced drag will increase as the effective hull area gets smaller. The hydrodynamic force per unit area has to increase to keep counter the weight of the boat (which has not changed). The effective shape of a displacement hull also changes with speed as seen by the water, but not anywhere as much as a planing hull.

For a typical day use boat starting from a stop and advancing the throttle slowly you will see at first a fairly linear correlation between fuel burn and mph as speed is increased. As the speed increases further and the hull starts to rise, the fuel burn (rpm) will go up substantially, but the speed increase will be less (the boat is essentially moving up hill as it climbs out of the water). Once the bow wave is crested the boat starts planing and the speed will increase rapidly. Once the boat planes, you are back to a fairly linear correlation between fuel consumption and boat speed. A plot of fuel flow versus speed will show a peak or break in the curve somewhere around the middle when the boat starts moving from displacement to planing mode.

Your argument is just a longer version of what I wrote...

 

[NYBo]

Re: I want a fuel-sipping cuddy!!

Maybe, on a good day you could get to 50 with a Big Block with a huge carb. sucking down 10+ gallons an hour, maybe...

That works out to 5 MPG, which ain't happening with such a rig unless it's going over a waterfall. More likely to be on the order of 25 GPH, or worse.

 

[Howard Sterndrive]

Re: I want a fuel-sipping cuddy!!

here's my 3.8L V6's absolute best mpg with aluminum prop. (I can get 5.1 with the SS prop)

 

[HeloMech]

Re: I want a fuel-sipping cuddy!!

To crap in in total privacy and stow extra stuff.

LOL!! I have yet to use the portapotty in my CC. I did sit on it once just to figure out how I would have to bend my body to fit in there. I could have rested my chin on the bow of the boat if the hatch opened the opposite direction. As it was, I could sit there and stare the driver right in the eyes while tending to my "business" lol. I'd need a umbrella if it was raining.

 

[25thmustang]

Re: I want a fuel-sipping cuddy!!

I rely on the manufacturer to label it. Regal calls my boat a cuddy, so I do the same. I do not think it's a cabin cruiser.

my boat:

A 25 foot Regal cabin cruiser:

The cruiser is clearly a lot taller. I prefer the sleeker look of mine.

The boat in the first photo (yours) has 6'3" of headroom?? That's impressive as a few 33'ers I looked at didn't have 6'3" of headroom!

 

[Mischief Managed]

Re: I want a fuel-sipping cuddy!!

The boat in the first photo (yours) has 6'3" of headroom?? That's impressive as a few 33'ers I looked at didn't have 6'3" of headroom!

In one tiny spot in the center of the cabin. The deep draft helps. It draws more than 3 feet with the drive up.