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#1
11-17-2018, 06:02 AM
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1976 SeaCraft 23 Sceptre
O Great SeaCraft Swami's, I come looking for guidance.
This showed up, and what a beaut, I have never seen a boat of this age as in great a shape, and she is a special one. 1976 23' SeaCraft Sceptre, with a 270 hp inboard, "V" drive and a tunnel. Owner wants to get "More Speed". Is this possible with this setup? She cruises around 21knts, he would love 10 more knts? I await your esteemed replies. 
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#2
11-17-2018, 10:20 AM
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Dang Ole, that thing is really, really clean! Kinda makes my clunker look like poop!! Hate to say it but I have no idea how to make it faster than the old "more HP is better" formula! I don't think the large diameter heavy props used on these boats were high speed type props. Good luck!
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#3
11-17-2018, 10:46 AM
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OK - this is something I spent a long time wondering about. I don't think your gonna like my answer much though.
Feel free to pick it apart, but I HAVE NEVER DONE THIS SO IT'S PURELY THEORY... On the 23 IB the prop pocket starts going to lower and lower static pressure as the hull goes faster and it is pumping water up to fill the pocket; lots of water - you very quickly get to a point where massive increases in HP produce only minimal increases in speed. Kinda like having a giant water scoop on the bottom of the hull. I think the only way around that is to relieve the 'vacuum' in the fwd portion of the pocket - either by moving more water (takes HP) or introducing air so that you are not 'scooping' water. You would want it to be effectively more like a Jersey Speed Skiff. I suspect an air vent would allow the pocket to ventilate and would stop/minimize the scooping of water but then you have big time cavitation issues with the prop (and maybe erosion on the strut/rudder if fast enough) - I think you would then need a surfacing prop at a minimum. And a whole lot of experimenting. And long discussions with Ken at Prop Gods. Did I mention $$$$ for time? It would be a really cool research project though.
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#4
11-17-2018, 05:38 PM
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Hey Strick, wake up!
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#5
11-17-2018, 06:53 PM
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Funny Mitch that you mentioned surface drive......
That was the first thing that came to my mind !! $250K on Ebay for the pair of Arnesons he will be good to GO ! Can you say Manatee slayer... 
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See ya, Ken ©
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#7
11-17-2018, 11:26 PM
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Lol Hey Oly! I have no comment other then nice boat and needs a bigger engine! My 23 Sceptre (actually a Tsunami) will be heading to Massachusetts soon. Big and I are working on a deal...
strick
__________________
"I always wanted to piss in the Rhine" (General George Patton upon entering Germany)
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#8
11-17-2018, 11:53 PM
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Yes cavitation and erosion/corrosion could happen. Those surface drives are worth investigating. But $250K. Wow. Transcontinental Tsunami. A Tsunami is hitting Cape Cod?
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#9
11-18-2018, 05:41 AM
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The only way a surface drive will work is to spin the motor inputting into a ZF transmission outputting into a simplicity drive. With the way the motor is moved forward it looks like it would have room for the transmission so it would likely be doable. You can find deals on used simplicity and other drives but even if you got a deal the motor would need serious upgrading and the pricing on SP props is beyond stupid. Cool as it would be the easiest and cheapest way to get a 31 kt cruise is with a DF 300 and a bracket.
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[b]The Moose is Loose !
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#10
11-18-2018, 09:18 AM
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Quote:
Transom, bracket, fill the hull bottom, be cheaper to sell this boat and start with another. Could do a waterjet. :-))))))
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Ya know someone told me one time they "taste like chicken"!! March 31st will be here soon and the idle zones will go back to normal.
Linear Mode
