Reasons for using a shorty drive
 

What are reasons for using shorty drives on certain applications. I want to put an older Alpha SS on my 20 foot Searay, but want to know the possible benefits. First I should describe my situation. My 383 powered 91 185 SeaRay runs in the neighborhood of 76 MPH. At this speed the boat is lifted very high out of the water, to the point that pretty much only the back couple of inches and the drive are in the water. At 73 boat will start bouncing up and down and side to side. Will going to a shorty gearcase improve this or would this be a mistake and make it worse. I understand that a shorty gearcase is sort of like using a Jackplate, but without the additional setback. Any ideas?

Re: Reasons for using a shorty drive
 

Dont know about the setback, but do you have tabs on your SeaRay? This might be a more cost effective way to resolve this prob.

E.S.

Re: Reasons for using a shorty drive
 

i dont think a shorty will help you. it seems like your goin faster than you should be in that boat anyway. you'll probably experience prop blowout as well.

Re: Reasons for using a shorty drive
 

I've got tabs on the boat, but I have them mounted too far inboard. That's going to change when I cut the thru hull exhaust holes as the rams mount where the exhaust is going to go.

Bruce, I know the boat is going faster thanit was intended, but it sure is fun. Prop blowout is not really a problem since I put the nosecone on years ago.

Tomorrow I'm going to measure the distance from the bottom of the boat to the prop shaft. I was reading in some other posts that you want to be around 2 inches or a little more. (This might be boat specific, but it should be good to know.

Re: Reasons for using a shorty drive
 

Oh and the boat is very similar to the old Pachange 19. The OAL is 20'2" and has very similar hull lines. I think they took a page from the 19 footer when they made this boat.

Re: Reasons for using a shorty drive
 

The chine walk is indicative of a couple of things. It could be something is worn in your steering. It could be a balance issue. It could be a proping issue. Driver skill and hull speed also play into this. A good driver can drive with some chine walk. Skill won't make up for defective steering or exceeding a hulls capabilities. Right now, I'd guess that you are exceeding the hull's design. A shortie lower will make this situation worse. Try a different prop first to see if that helps. I'd try a Hydromotive Q4 if you can find one small enough. That's a stern lifting prop and it sucks getting on plane, but it's a very smooth high end prop. If you want more speed, you should also start looking at hydraulic steering. That alone, could help dramatically.

Re: Reasons for using a shorty drive
 

Well like I said it start at 72-73 and the boat goes 76 so I do have to drive through it and it has been doing it for a couple years so I have gotten pretty good at reading it. I won't let anyone else drive it at that speed because I don't know what they will do.

Anyway I tryed a Bravo 1 22 in prop a couple weeks ago, but it did not perform very well. It vibrated a lot at speed, but that might have just been a goofy demo prop. It also rocked back and forth a lot sooner than the 3 blade. I'm running a 21 tempest right now and this has been the best prop I've tested since it came out.

I'd like to put the hydraulic steering on it, but 3500 buck for that... I might as well sell this boat and get a bigger one and start over.

Re: Reasons for using a shorty drive
 

Sounds exactly like my boat before hydraulic steering,i also had a speed around 72-78 that it would get downright ugly,the nose cone makes it worse without hydraulic steering (if you didn't already know that). Maybe you could at least put a stabilizer on it,i think a shortie drive would make it worse yet,Smitty

Re: Reasons for using a shorty drive
 

Where can I find steering stabilizers? Also, without the nose cone the prop will blow out at about 64mph. Thanks for the info guys.

Re: Reasons for using a shorty drive
 

Drew marine makes them. If you never are going to add more power or look for more speed, then the stabilizer will help. If you are, then go hydraulic. A full system is the best, but a add-on ram is better than nothing.

Re: Reasons for using a shorty drive
 

Just a small piece of advice. From my experience. Before you go and spend sick money on Hydraulic and any other power or handling upgrades, You may consider a bigger faster boat. A full hydraulic system can cost as much as 5k. and race tabs (K-planes) another 3k. Bennet tabs dont work well at speeds of 70 or better.

Just my .02

Re: Reasons for using a shorty drive
 

I understand your not wanting to spring for hyd steering,your boat is a accident waiting to happen without it but thats your choice! I built new stainless trim tabs to replace part of my bennets (i'm cheap sometimes) and it also helped,Smitty

Re: Reasons for using a shorty drive
 

Hey Artic, can you email me that picture. I'm not a paying member yet. [email protected]

Re: Reasons for using a shorty drive
 

In all the chinewalking demon boats I've had, a shorter drive has HELPED chinewalking. Keep in mind, that you still gotta lift the bow, and a shorty won't lift as well. If you don't need a lot of trim to get her aired out, then a shorty may work better than you'd think.

But don't even THINK about running a 80mph chinewalking boat with stock steering. You'll never have the solid link between the steering wheel and the drive that you need.

Before spending any money, you may want to remove the power steering and hook the Morse cable directly to the drive tiller. This will give you a more solid connection. It'll kind of suck cause you'll lose the power steering but it will be safer. It will also make your arms bigger.

Re: Reasons for using a shorty drive
 

well I measured how far bellow the stern of the boat the centerline on the prop shaft is: 8 1/2 inches. Does that seem like a lot? Anyway lifting the bow is not a problem with this boat. I am going to put a drew marine stabilizer on the boat also.

Re: Reasons for using a shorty drive
 

8 1/2"....That is deep. but, thats the way pleasure boats are set up. Non Stepped Race boats are usually around 3 to 4 inches below the bottom of the boat. If you put a 2" shorty on you may see some increase in speed and handling.

Re: Reasons for using a shorty drive
 

76 MPH with a 21 pitch prop? How many RPMs are you turning? :eek:

Re: Reasons for using a shorty drive
 

I take it you mean reduced the chinewalk ?



I think he is referring to Speedo speed @76 not GPS. :rolleyes: :rolleyes: :rolleyes:

Re: Reasons for using a shorty drive
 

yes. In outboards, jacking the motor higher on the transom usually REDUCES tendency to chinewalk.

Steering torque goes thru the roof, and you'll grow a gorilla arm, but chinewalking reduces and speed goes up.

Re: Reasons for using a shorty drive
 

The motor is turning about 5400 RPM and yes this is speedo indicated. I don't have a GPS redily at my disposal.

Yes I mean to reduce the chine walk. So if my drive is currently at 8.5 inches and the Alpha SS drive will cut 3 inches, that gives me 5.5 inches. I was pretty wowed when I saw the cavitation was nearly even with the bottom of the transom. Will there be an adverse effect having the top side of the prop blade spinning slightly above the stern. Or is this going to allow me to run a lager pitch prop due to the slippage?

Re: Reasons for using a shorty drive
 

Alpha SS is a great dive... I had the exact same set up on my 22 Velocity for a while.. Ran 70.1 with a L&S Box... Just a bit of warning in advance that drive can't handle much more power so if you are ever considering more power your gonna need another drive.... Imco single ram PS @ 1200 bucks is one of the best investments i made in my boat.. its a dream to drive... I can now let go of the wheel @ 77mph.
And its just down right safer .... Snap a steering cable 75 and you're not gonna like the ride! Can you get your hands on the shorty and give it a go before you buy it.. my bet is that once its on your boat its not coming off.. less drag = less walk. Love the idea above of a Hydro Q4 the stern lift may help out a bit! great little boat and sure sounds like you've dialed her in well! Good luck with the Alpha SS MW

Re: Reasons for using a shorty drive
 

Thanks for the info Velo. Actually I'm buying the gearcase and taking the internals out of my gen 2 with the heavy duty gears and putting it in the bare upper. Thank single ram price doesn't seem to bad. I would liek to try a Hydro Q4 but not to many dealers up in Minnesota that I know of. The L&S box I'm assuming your taking about an extension right? How hard is it to put one of those? one and how much do they cost

Re: Reasons for using a shorty drive
 

Wow my IE errored out and it screwed up the words in my post. This is how it is suppose to look.

Thanks for the info Velo. Actually I'm buying the lower gearcase and taking the internals out of my gen 2 upper with the heavy duty gears and putting it in the bare upper. That single ram price doesn't seem to bad. I would like to try a Hydro Q4 but not to many dealers up in Minnesota that I know of. The L&S box I'm assuming your taking about an extension right? How hard is it to put one of those on, and how much do they cost?

Re: Reasons for using a shorty drive
 

AC... I had the oppisite problem.. I needed the Bow lift on my boat which was the reason for the stern jack.... There are many arguments for the Box, both positive and negative...Thought I can say for me it worked very vell.. its a simlpe 6 bolt hook up maybe an hour @ best... no clue as to cost these days...Theres a good article in a back issue of Poker Run mag that explains the theory behind the box... heres a link...
http://www.land-and-sea.com/public/a...ns_article.htm good luck! MW

Re: Reasons for using a shorty drive
 

ACrooks69, I'm running an Alpha SS on an '88 Baja Sunsport 196 with a 11.25:1 Chevy 357. The previous owner installed it and claimed that he gained 4 MPH and better handling. He also removed the hook from the last 6" of the hull. Currently, the boat runs 78 @ 5900 with a stock Mirage 23P. With a 125HP shot of nitrous, I've run 84 @ 6300. I'm still dialing in the 150HP shot, but I expect to see around 86-87 with the cooler weather that's coming.

In what conditions are you trying to run over 70? If it's anything other than smooth water, you'll see that chine walk. I have to get out on the water by 8AM on a weekend to run high speeds.

Re: Reasons for using a shorty drive
 

Plum, Actually it chine walks worse in calm water. The boat likes a little chop to skip over the waves. What is your prop shaft height in relation to the bottom of the transom?

Re: Reasons for using a shorty drive
 

I don't know offhand, but I'll measure it. However, I believe that the SS is 3" shorter overall.

Re: Reasons for using a shorty drive
 

Here's an older pic of the SS with a Spinelli prop:

http://img.photobucket.com/albums/v2.../Baja/nos1.jpg

Re: Reasons for using a shorty drive
 

ACrooks69, my prop shaft is 5" below the hull.

Re: Reasons for using a shorty drive
 

Plum, what are you running for a prop? I don't feel so bad now yanking the guts out of my good unit and puttig it in the old drive. I think 5.5 inches is plenty of depth for running this hull. Granted hull it is a little steeper than yours but it should be OK.

Anybody got the quick mod for putting a gen 1 Alpha 1 drive on a gen 2 bellhousing? I know there is something I have to do whith the shifter foot. But that is all I have been told.

Re: Reasons for using a shorty drive
 

As I mentioned above, I'm running a stock Mirage 23P. Check out this thread for swap info:

http://www.offshoreonly.com/forums/s...=Alpha+SS+swap