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-   -   Hull tuning. (https://www.offshoreonly.com/forums/chris-craft/206141-hull-tuning.html)

Scorpion23 04-03-2009 04:54 PM

Hull tuning.
 
I have a 1986 CC Scorpion 230 Ltd. Ive gutted the boat and replaced the transom and the floor supports. I removed the 350 and am building a 454. I replaced the Alpha with a Bravo gimble housing. (not sure if im running the BIII I have already or finding a BI) I raised the propshaft height 2.5" already and started taking the hooks out yesterday. Other than removing the bottom paint, can anyone think of anything else I should be doing to update the hull while everything is apart? And has anyone else raised the drive height of a 23 or am I the guinea pig?:rolleyes:

Scorpion23 04-05-2009 12:22 AM

Anyone have any ideas? Length of tabs maybe?

DareDevil 04-05-2009 02:54 AM

Hope those hooks wheren't in there for a reason !!:eek:

540phil 04-05-2009 09:28 AM

Actually I'm glad your doing it now. I bought a 454 version last year and am redoing interior and the like now, I have 2 alpha ss drives alnong with the standard drive that is currently on. I havent had a chance this year with the ss drive yet but will tell of results when used. Fortunately I had no glass work needed. Puting in full set of livorsi and new vinyl.

Scorpion23 04-05-2009 05:44 PM

540... What was your top speed with the 454? Was the engine stock?modified? Also, if you have the boat near you, can you do me a favor and measure the height of the water line from the bottom or the swim platform. I want to make sure that my exhaust and swim platform wont be under water with all the extra weight from the 454 and a BIII. If its not that easy to do forget about it, dont go out of your way. Im just curious. Thanks for your time.

Scorpion23 04-05-2009 05:47 PM

As I understand it, the hooks are there to keep the bow down at all times, the more boat out of the water, the faster and more stable the boat is at higher speeds. Please correct me if im wrong before I do something ill regret. Tks.

TomZ 04-05-2009 08:43 PM


Originally Posted by 540phil (Post 2836591)
Actually I'm glad your doing it now. I bought a 454 version last year and am redoing interior and the like now, I have 2 alpha ss drives alnong with the standard drive that is currently on. I havent had a chance this year with the ss drive yet but will tell of results when used. Fortunately I had no glass work needed. Puting in full set of livorsi and new vinyl.

Wanna sell one of your Alpha SS drives??

DareDevil 04-05-2009 09:06 PM


Originally Posted by Scorpion23 (Post 2836844)
As I understand it, the hooks are there to keep the bow down at all times, the more boat out of the water, the faster and more stable the boat is at higher speeds. Please correct me if im wrong before I do something ill regret. Tks.

You are kind of right,,but it also is more stabil with the hooks and now your adding weight to the a$$ of the boat and have more power ,,,so it should be faster anyways but keeping the nose down is going to (maybe)be a problem with more weight and the higher X-dimension at top speed ,,,safety is what counts not just speed ,,,,if the boat is 3 MPH faster but u can't run it ,,,what sence does it make ?!:rolleyes:

Scorpion23 04-06-2009 09:44 AM

Agreed... I will leave as is. Thanks

Scorpion23 04-06-2009 09:46 AM

But then again, its 3 mph. :evilb: Just kidding.. Tks again.

540phil 04-11-2009 07:40 AM

Well I believe the factory posted the Scorpion 23 @ 52 mph with a stock 330 454 @ 4400 rpm and 46 mph for the 260 hp, thats about all there is unless you add hp, shorten the drive or raise the rpm's. Is the B3 a duo prop? If it is you certainly will not need the additional prop for ventivation problems unless you raise the drive to a point you do. (Tom Z), not right now, but check back latter in the summer, I'm having a merc dealer go thru them now, they will be perfect. I will post top speed with the standard alpha 1.5 ratio drive then #s on the SS.
First I want to get the livorsi prop slip guage / gps speedo.
I will say I ve never had a scorpion 23 that was light in the bow, between the deep set standard drive height and the 454
weight, mine have always been tail heavy. (Scorpion 23), the distance between the swim platform and the water line is maybe 2-3". If you are putting in thru hull exhaust you will have to go thru the transom and thru the swimdeck. Be careful
in not going to deep, you will suck water and bend valves or to shallow as the water you are pumping out will come back when you get off the throttles. Better find the stock setup to alleviate these potential problems, though rare they were available.

540phil 04-11-2009 07:43 AM

Correction

I will say I ve never had a scorpion 23 that was HEAVY in the bow

Scorpion23 04-11-2009 11:16 PM

My boat already has the thru hull exhaust with the silent choice diverters. The only difference is going to be that I will not be using the 3" riser spacers that were there from the factory due to the raised engine/drive height. I have new stock Merc manifolds that I will use for now (I know they dont flow worth a sht but I cant afford any others yet) I also have a set of stainless merc elbows that i will get rid of. I will get a set of flange to flange elbows, cut a flange to fit the outlet surface of the elbow. I will weld a 3" inner pipe and 4" outer pipe to the flange that mixes water with exhaust as far back as possible. I dont think i will be able to use the silent choice anymore due to the camshaft that will be in the new motor. I also am thinking about adding at least one set of flappers to the system when im done. As for the water line, i think that the water line was about 2" away from the bottom of the swim platform with the Alpha and small block. I hope my platform isnt under water with these mods. That would suk! I think ill leave the hooks in for now and see what the boat does with the new mods. Ill be happy with 60-65 mph with 400 hp. Im also looking into a hydraulic steering setup and thinking about extending the bennet trim tabs that are already on the boat. Is it possible that my 23 Scorpion LTD with thru hull exhaust came with a big block and someone just threw in a small block? Someone on here commented that the LTDs came with 454s. I would also like to post pics here but cant find out how. Can anyone help with this?

DareDevil 04-11-2009 11:22 PM

I know they made them with either BB or SB !!!!

Also i realy don't think its such a good idea to raise the engine up or the drive,,,leave the engine where is and get a 2 inch shorty !!!!

U raise alot of weight which isn't that smart in a single engine boat !!
But thats just me .

Scorpion23 04-12-2009 04:39 PM

I already raised the drive/engine 2.5". All glassed in and ready for gel. I had to replace the transom and I cant afford a shorty so I had to make the best of what I had.

DareDevil 04-12-2009 05:40 PM


Originally Posted by Scorpion23 (Post 2842336)
I already raised the drive/engine 2.5". All glassed in and ready for gel. I had to replace the transom and I cant afford a shorty so I had to make the best of what I had.

Well,,lets see how it works .....i quess !!!!:party-smiley-004:

Good luck ,Happy EASTERN and stay safe !!!:ernaehrung004:

Scorpion23 04-12-2009 06:00 PM

Same to you and hope all is well.

DareDevil 04-13-2009 03:44 AM


Originally Posted by Scorpion23 (Post 2842370)
Same to you and hope all is well.

Thanks,,and let us know how it works out !!!!!!:ernaehrung004:


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