Shippng a yacht

[Tillikum]

Originally Posted by Montanan

Cringe worthy, trailer hauling.

Somebody didn't notice it was a well cambered road.

And of course forgot to strap it down to the trailer, though the benefits of doing so in this particular scenario would be questionable as the plastic fantastic floating condo probably has nowhere a meaningful tie-down could be secured.

I wonder if the two lines going over the bow were all that held it onto the trailer?

As for controlling the outboards on the intended move, a couple of able bodies and a few walkie-talkies, with pre-arranged signal system as a backup?

Rent some Tidy Tanks for the fuel, or buy a horizontal home heating oil tank or two and lay on some old carpet in a convenient spot and run lines from those? Only 317 US gallons in one of those however.

[s/v Jedi]

Originally Posted by MicHughV

Outboards can burn a prodigious amount of fuel.
I have twin 150's on my fishing boat and at around 3,000 rpm am burning plus/minus 13 gal/hr. I'm sure twin 75 hp will be less, but 'jes saying.
An 8 hour day on the water is gonna suck some gas and I'd anticipate about a 50 gallon burn rate for the day.
Have no idea, what speed you'll be able to make, but likely less than hull speed.

Really?! At 6 knots?

[MicHughV]

I have a fuel meter on my fishing boat, so I can tell at a glance what the fuel consumption is.
At low rpm, ie, not on plane, the engines suck as much fuel as when on plane, as they are trying hard to push that hull thru' the water. Engines are fuel injected

Once on plane, about 3,000 rpm is the minimum rpm it takes to keep the boat on plane, but it's barely there, 3,500 rpm and the boat is happier. You can hear it in the engines. Sometimes, one engine is running 100 rpm more than the other and this also causes the high rpm engine to labor, as the other engine is not doing it's job. Both engines at the same rpm can be easily heard by the engine note.

Finally, engine trim can also make a difference, as well as weight of boat and fuel

Through all this, I've noted the engine fuel consumption at different rpm's ,trim, load and speed.
Many variables to consider as all these little things affect fuel consumption.

I don't see a heavy 53' powercat, pushed by twin 75's, attaining anything beyond hull speed of that boat is my opinion, and likely around 6 knots would be a reasonable expectation.

Not sure how the OP would plan on attaching these engines either as some type of bracket would have to be fabricated and outboards typically don't have the prop very deep below the surface either, so they could life out of the water in a big wake or have other cavitation issues.

Doable, yes, but ??????

[s/v Jedi]

Originally Posted by MicHughV

I have a fuel meter on my fishing boat, so I can tell at a glance what the fuel consumption is.
At low rpm, ie, not on plane, the engines suck as much fuel as when on plane, as they are trying hard to push that hull thru' the water. Engines are fuel injected

Once on plane, about 3,000 rpm is the minimum rpm it takes to keep the boat on plane, but it's barely there, 3,500 rpm and the boat is happier. You can hear it in the engines. Sometimes, one engine is running 100 rpm more than the other and this also causes the high rpm engine to labor, as the other engine is not doing it's job. Both engines at the same rpm can be easily heard by the engine note.

Finally, engine trim can also make a difference, as well as weight of boat and fuel

Through all this, I've noted the engine fuel consumption at different rpm's ,trim, load and speed.
Many variables to consider as all these little things affect fuel consumption.

I don't see a heavy 53' powercat, pushed by twin 75's, attaining anything beyond hull speed of that boat is my opinion, and likely around 6 knots would be a reasonable expectation.

Not sure how the OP would plan on attaching these engines either as some type of bracket would have to be fabricated and outboards typically don't have the prop very deep below the surface either, so they could life out of the water in a big wake or have other cavitation issues.

Doable, yes, but ??????

You are using 13 gallons per hour of fuel for making 6 knots. Something is very wrong with your boat. Even my 64’ boat uses a fraction of that… I only need 20hp to maintain 6 kts.

[MicHughV]

You some things confused, on my fishing boat at around 3,000-3,500 rpm, I'm doing 25 knots or so...burning around 13 gal/hr for both engines..

If the OP wishes to use outboard power on his 53' powercat, the two 75's mentioned elsewhere in this thread, my opinion is that it will likely cruise at around 6 knots..

[s/v Jedi]

Originally Posted by MicHughV

You some things confused, on my fishing boat at around 3,000-3,500 rpm, I'm doing 25 knots or so...burning around 13 gal/hr for both engines..

If the OP wishes to use outboard power on his 53' powercat, the two 75's mentioned elsewhere in this thread, my opinion is that it will likely cruise at around 6 knots..

I’m afraid it’s you who is confused. After your claim of 13 goh I asked “really?! At 6 kts”? And you answered “yes, at low speed fuel consumption is the same because the boat is struggling “

[MicHughV]

nah, I'm not confused.....

[s/v Jedi]

Let me help you remembering what you wrote:

Originally Posted by MicHughV

I have a fuel meter on my fishing boat, so I can tell at a glance what the fuel consumption is.
At low rpm, ie, not on plane, the engines suck as much fuel as when on plane, as they are trying hard to push that hull thru' the water.

[MicHughV]

Yes, that is correct, at low rpm, when boat is not on plane, it's trying hard to climb over the bow wave, and is sucking as much fuel as if it were on plane.
To get the boat on plane requires goosing the engines to 4-5,000 rpm, before backing off.
It will not get on plane at 3,000 rpm or less, it will wallow.

Not quite sure what you are driving at here, I know what I said.

[Lee Jerry]

Yamaha provides "Performance Bulletins" for most of their engines. Here is one for a twin engine, 2x 150 hp, center console. The graphed data looks like this:


The tabulated data is here:


As you can see, fuel consumption (gal per hr) increases "steadily" throughout the RPM range. (Not to be conflated with mi per gal.)

[Lee Jerry]

If we can get back on track a bit, Leopard also provides trial data for the 53PC (which, as an aside, appears to be only 50.5 ft long ):

https://www.leopardcatamarans.com/wp...-8LV-370hp.pdf

[s/v Jedi]

At 6 knots it will consume only a couple goh, not 13gph. I think it may be as low as 2gph.

[Johan Leopard51]

Some cross-purpose talk in these debates!

Forget about attempting planing speed on the Leopard, as anyways not feasible in the ICW. Maybe 6-7 knots?

At 1500RPM the two Yanmar happily get it going and sustain moving the Leopard at 7 knots (and consume 5 Gal/hour which is irrelevant in this debate). At 1500RPM the two Yanmar together output (crankshaft) only about 100 mhp total.

But that 7 knots maintained at 50 mhp per motor is with the gearbox and props on the Leopard. One can’t simply look up 100 hp to work out how much outboard needed.

For certain, two 75Hp outboards with their normal props will SUCK fuel moving that Leopard along at 7 knots IF they can even get the Leopard to 7 knots. Stopping the Leopard would also be interesting. I’ve towed a large floating jetty for a canoe race with small boat and over 400 Hp outboards and it feels like time stands still to get going. It gets easier with momentum built but the outboard gearing and props are simply not designed for that job.

If it were my project I would first prize put her on deck of a barge or coastal freighter or float her and see if a barge can tow her home. It sounds like the buyer still has a precondition on sale that hull can be repaired so then towing her seems like best option.

[BlueH2Obound]

Originally Posted by s/v Jedi

I’m afraid it’s you who is confused. After your claim of 13 goh I asked “really?! At 6 kts”? And you answered “yes, at low speed fuel consumption is the same because the boat is struggling “

Originally Posted by MicHughV

nah, I'm not confused.....

You two folks want to take it outside and drop your drawers? You're not helping the OP with his problem, you're just cluttering up the thread . . . .

[CarlF]

As an owner of a 50ft Leopard sailboat, I'd strongly suggest that you first have it towed (or trucked) to Dania Beach (Ft. Lauderdale) to have JustCats advise on the work. While they are expensive, they know the Leopards inside and out (they do the warranty work). I've seen them tackle bigger jobs than yours. And they have a travel lift that can lift her. Or pay one of their guys to drive down to Key West to look at it.

The 53PC is a very complicated boat - expecially the electrical system but there's also a lot of structural components that won't be familiar to guys who haven't done a lot of work on big, new build powercats.

Once there's a plan, you can decide what work to do where.

Letting a guy who's never worked on a Leopard loose will just have you fixing it twice - and you'll be paying an hourly rate for his education. Or worse, you'll have a boat that can't pass an insurance survey (which you'll need to get insurance and you need the insurance to get a marina slip)