1050 MANS in a 46C

[captddis]

Alfonso, here is the pic of my factory cut down keel.

[cruzcol]

CAPTDDIS
Thank for the photo
Alfonso

[stormchaser]

I'd think that step one would be fix the trim tabs and sea-trail it again. You can correct a bit of lean just with the tabs...might be all she needs.

[REBrueckner]

"My question, is the boat built to take the kind of stress and twisting that such high horsepower produces.."

couple of thoughts:
that will depend in part how aggressive operators are when in heavy seas...that will begin to tell the tale. Running faster in calm waters with a controlled acceleration can ease such stresses....

Also, with some repowers, heavy "I beam" engine bed extensions spread out stress and weight over a greater hull area.

One factor in favor of higher HP relative to older 71 style engines is much more HP/lb of engine weight....I wonder what the weight of the new MAN's is relative to the old 8V71's or 8V71TI's....

Pretty soon they'll have to start installing camper style "bump outs" to make for more hull side room.

I still remember running a friends 40 ft Matthews sedan in Florida with my dad many years ago...the 1949 wood boat had a pair of new 350 HP Chrysler gas engines...Around 3000 RPM the round bottom was so high out of the water she'd begin to wobble and tip from side to side...no problem, we just ran the engines nice and easy....and the boat was still "fast"....

[seacolt]

Anyone know if there a big difference in the keel of a series 1 compared to the series 2 46c ? I have always wondered how my series 1 46c would ride at 26 knots in a heavy chop.

[saltshaker]

Anyone know if there a big difference in the keel of a series 1 compared to the series 2 46c ? I have always wondered how my series 1 46c would ride at 26 knots in a heavy chop.

It runs great. I have a '74 46C and she runs better at 23-24kts than she does at 18-19kts. Boat gets up a bit higher and really knocks down the chop. Spray seems a bit less at the higher speeds. The 46C HP boats w/8V92's are the same hull with the keel shortened. If you are referring to the early 90's 46C, that is a completely different boat.

[krush]

Needs more power, that MAN isn't enough. Stick in a gas turbine from a helicopter.

[jim rosenthal]

Someone did that in the eighties- there was a boat built in Florida which had 8-92s as low speed engines, and a Lycoming or Textron gas turbine for high-speed power. I think it was built by Lydia Boatworks and the name of it at the time was "That's My Hon" or something like that. I'm not sure it was ever finished, and I think it passed through several hands and a few sets of engines were tried. Years ago, there were a series of high-speed big boats built with turbines, and I think some with surface piercing drives such as Arnesons- I recall reading about them in PMY and other similar magazines. All crazy stuff- not really usable boats and the expense was incredible- built by bored rich people with more money than sense. Such people used to exist, believe it or not, along with diesel at 75 cents a gallon, which made it possible to run such a boat.

[SKYCHENEY]

Hull speed and maximum designed speed are two different things. Hull speed is the calculation of the square root of length water line times 1.34. This is the maximum speed a hull can travel through the water before it starts to climb onto plane or push water.

What you are referencing is maximum designed speed which would be the top limit of the hull before the handling gets out of control or it breaks up. The first is easy to calculate, the second is much more difficult.

[captddis]

I like speed but, when you double the power something has to give. I am not sure exactly what they mean by hull speed other that that is the max speed the hull is designed to perform at without handling problems or stress problems. Seems like the horse is out of the barn, homework should have been done before the change was made.

If anyone an give me a better explaination of hull speed please do. Dead rise is also one that I don't fully understand.

There is a 43 or 45 Hatt in Bradenton, or was in Bradenton with Rolls Royce engines in her. Installed by Tom Slane, perhaps Slane is the best person to contact. Other than it is fast, I have never heard about how she performs. The owner did buy a new boat that was designed for high speed.

Keep up the good work guys, I am learning much from tis forum.

That was a 46C HP that was cut down into a express. The hull was already engineered to accept the power.