reinventing the wheel

bob lico · Post by **bob lico** » Apr 21st, '10, 15:35

we really reinvented the wheel. quite i few people peak under the boat to take a look before splashing. trick out strakes,structs, rudders,cutless bearings ans needless to say props were done to the max with the addition of prop speed this year.rocky, sim another thank you the first indication of sucess was lower then factory idle at 600rpm the lowest i ever had them with these single lever controlls.took her out of the basin with both engine in gear at idle she was at 8mph so i turn around went back and put the back up props same proportions but 3 blade 23.5' pitch about what you run on a 250hp cummins.took it back out and ran 5.2 at idle .i can accept that. so i am underprop quite a bit. she ran 33knots wot and hit the pins at 2925 rpm easy 36 knots with other props. back off to 2500 rpm at 30knot slow cruise and and 200 rpm off the rated speed of 2800rpm would be about 31 knot cruise. -----nice to have full control of thottle for first time .at 2300 /28 knots fuel economy was out standing.
we WON--------------

Bruce · Post by **Bruce** » Apr 21st, '10, 18:44

Bob,

Rocky · Post by **Rocky** » Apr 21st, '10, 19:59

Bob your welcome, we help each other out! Your 31 sounds real nice.
Aint nothin stopping the torque of those diesels, bet that's great having that kind of power.

bob lico · Post by **bob lico** » Apr 21st, '10, 20:09

i have to say one thing those bright yellow painted props with the prop speed are butt ugly! for those of you interested a 31 bertram rises of outside strakes on to inner strakes at 37 to 38mph. i could only estimate after 40 mph the boat would be "on the edge" and downright dangerous without the captain`s rudders keeping you planted in a straight line.

Carl · Post by **Carl** » Apr 22nd, '10, 09:02

Thanks for the update Bob!!!

So you have full throttle motion at the helm...excellent!!

You would know better then me...but can't you take some Pitch out of the wheel to lose speed at idle and add Cup to gain back your top end?

Bruce · Post by **Bruce** » Apr 22nd, '10, 09:40

Bob,
The issue never was a straight line run at high speeds on the 31.

It will always be excessive lift due to speed and hull design and making turns, falling off and being grabbed by the water and all of a sudden heading hard stb or port possible throwing people off, down or injuring them.

After all what's the use of the extra speed if when you have to make a turn, you have to back off the throttles?

5 point restraints should not be required on a 31.

bob lico · Post by **bob lico** » Apr 22nd, '10, 09:45

sim throttles are perfect and the throw is enormous from 1" off dashboard to all the whey down to doors! translate to infinitite control from idle to wot. incidently the prop speed affects the props in reverse .you have to give more thottle to move boat but i can go in reverse at idle like 2mph.i remove 21/2" of pitch from one set of props to the other to slow the boat down at wot.the cup on both is "off the wall" no props in the world have cup like these.bill stevens from wesco representing the cummins factory will come to the boat to take full review as it stands now these are the most effincient 315hp in the world.cummins have records of every installation made. the engines must be review in order to qualify for warranty .i don`t want to get off on the wrong foot as my intentions boat speed is not the challenge but goes hand and hand with effiency. phoenix can make 30knot cruise to canyon fishing(weather permiting )at the maximun effiency of 10% 0ff the pins . that relates to 280rpm off 2800rpm max about 2520 rpm.that is 300rpm less to do the same speed on the best installation. so even if you bring it down to 2300rpm you are going the same speed as another installation at 2600 getting great fuel economy and that what it is all about. don`t forget we have water temp at 62 degrees during august these numbers will be off somewhat due to fuel temp and fresh air temperature.

bob lico · Post by **bob lico** » Apr 22nd, '10, 09:55

honest to god bruce you have to see and feel it to belive it will you be coming to greenport in august i want you to do a wot turn i can`t belive it myself . without new windshield i belive i would develope a stress crack around mid ships you can feel tremedous stress during sea trial wot turns .does not dig in because she riding so high in water column but possibly would chine walk lock to lock turn above 38mph.

Bob H. · Post by **Bob H.** » Apr 22nd, '10, 10:48

Bob, Sounds like you nailed it...Id like the specs on those props...Im running basically the same engine/gear set...and a spin down in greenport would make my day...before we get to swiggin bertram juice...BH

Dug · Post by **Dug** » Apr 22nd, '10, 14:50

Bob,

Don't hit anything, ok?!

:)

Dug

bob lico · Post by **bob lico** » Apr 22nd, '10, 16:03

bob for one short moment just a little pucker factor . going into a turn at 38 sitting on the bridge with my steering (race car style) you definitly feel the g-force . the boat lays over quite a bit and turn like a high performace boat ,of course the reverse chine does not help matters but only a fool would make turns like that in the bay ---man it`s fun!!! during the year i will have a chase boat photo and i will post. bob there is no one item it is simple stuff like putting a 6" cutless bearing in a 5" struct forming a 1" pertrusion like a step to the struct basicly faring the struct at the cutless bearing end . the most important performace feature would be putting the racors in the bilge and somthing like the cutless bearing the least. like i said bob 3 to 4 knots faster then a similar installation is tremedous fuel economy .somebody like you who fared the bilge might think about truing up the strakes but anyone else would laugh . this is a carry over from race boat days but at diesel approaching 4.00 this summer nothing is stupid!!!

Bob H. · Post by **Bob H.** » Apr 23rd, '10, 08:20

Bob, I faired every inch of the hull above and below the water line, longboard and faired the bottom too, worked on the strakes for hours, got them as flat and true as i could. BH

bob lico · Post by **bob lico** » Apr 23rd, '10, 08:48

did you do the fiberglass shaft log /pss seal routine?

Raybo Marine NY · Post by **Raybo Marine NY** » Apr 24th, '10, 17:21

I will set the race up Bob

wmachovina · Post by **wmachovina** » Apr 24th, '10, 20:15

speed is a wonderful thing-my 250s get me 26kts. at 2400,awesome, nothing too rocket science, 4blade 21x23 w a little cup. what impresses Th s#$^ out of me is The ability to sustain 15kts in 3-4 ft slop going offshore. Set a speed and it just goes,goes, goes and I don't think it burns any fuel.Bob-I appreciate your work at the finer edgeWhen the Porsche 917/30 killed the Maclarens and the can-am ,Porsches answer was already built, flat 16 twin turbo 2000hp for a 1200# car. We need your madness,prost!! Bill

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reinventing the wheel

reinventing the wheel

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