Scx-4
 

What'd you put it on?
Where's your propshaft centerline compared to the running surface of the hull?
Do you have spacers,

My propshaft is even with the bottom of the hull. No spacers. I'm thinking about adding spacers but how thick?

The whole reason for that drive is to run it surfaced. I would think that you should go higher and run bigger diameter props with as many blades as you need to get on plane.
I plan on running one soon. Mine should be 3 inches above the bottom of the running surface.

I'd have to raise my engines to get the propshafts higher which I'm not going to do so I'm stuck with "what it is". I hear about "skiing" the drive and understand it so I'm wondering about sinking it deeper. Another reason for the -4 is reliability and depth adjustability, if you can't fully surface it.

I would not go lower , on my 42 lightning when I went from standard SCX,s to the -4,s I was 3.5 above the bottom and had blowout @ 100 or so the boat hooked R or L no spin out thank god she stayed up right put 2 inch spacers back down to 1.5 above where it was set up to be and worked great . I assume your using #6 props .

I have 6 props.
Slip is 16-18%.
A friend put on standard SCX's with the 1400 lowers and he's 2" below the hull with 9% slip and no loss of speed over the SC's he had.
My boat's faster and handles better with full tanks so I'm thinking that going deeper may give me less stern lift.
Does Brett have an SCX spacer program? Where the heck should I start?
Vid of the drive at speed shows that the water is hitting the drive at about the center of the bullet/propshaft.

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I have a pair of -4 2 inch spacer,s . If I remember right I had like 18% slip also .

I would try more blades on the props first to bring your slip down. TOO low of a slip # breaks drives. Why do you think that You need to change something? Just the slip # or is there another problem.

I don't have a slip problem mine is 8%. but what im getting is some serious chine walk at about 105. my lowers were blueprinted at Wilson. my propshaft is also even with the bottom, but mine is a side by side. according to Wilson I need to take some diameter out of the prop go from 17 to 16.75 or maybe even 16.5, because we are spinning them over 6000 rpm. the boat is at Reggies having a new dash put in, he sent the props out to Wilson. Just waiting to get everything back together to try.

It's faster and handles better with full tanks which hints that the stern is lifting too much. More blades would probably add to this. A 20 rake 37P would be nice to try but a spacer might do just as well for less $$$$

There are many others having issues dialing in thier SCX-4 but they won't post on OSO.....good luck getting her dialed in bud.

Thanks for keeping us updated

This is a tough forum to post on and get helpful feedback, a lot of people just want to go into trash mode. So many people just keep to themselves. That being said heres what I have learned about the scx-4's having owned them for 3 plus years. They have a really big nose one them, needed for the large gears. This has caused a problem with lift. imco has extended the skeg up to the front of the bullet, not sure how that works haven't got to try one. they claim it really helps? If your running 6 drive props ( I am) they seem to like a lot of rake, Mine are 18 wish I had 20 or 22. The drive seems to be built very rugged. pulled back cap off gears look new. My issue is stern lift once you hit over 6000 rpm hang on you now are lifting the boat off the strakes. Wilson did blueprint these when they were new, talking to them they claim 17" is to big when spinning them that rpm they need to cut them to 16.75 or even 16.5. My goal when I built the boat was to have one I could run at 80 all day with no issues. I have done that, so how much money do I spend trying to wring every last mph out of this. The boat will run 105 any day with full tanks empty tanks 1 person or 5 people. right up to there it is very well behaved, but push it past the 6000 rpm mark and hang on. My boat is currently at R lll"s getting a new dash, he has sent the props to Wilson and will run it when it is all back together. If that helps great if not not sure how far I care to chase this. By the way my boat is a side by side, If it was a full stager not so sure I would be having these issues.
Offshore Unleashed is one awesome boat you got yourself a keeper.

Thanks KW that's the plan!

Sounds like you are on the right track with your plans. The strength and reliability is awesome! Would be great if WCM could cut you a deal on modifying your lowers to match the newer imco skegs,and reblueprint. Not sure how much work would be involved. I do have another friend with a twin step V Hull that bow steers with to much stern lift at speed, so your not alone.

Don't be scared to cut down your props I have run 15.5" and 16.5" diameter on unleashed and she feels great. But I agree its a weird mental thing that we "THINK" we need larger diameter props. There's a lot more science to it then that but for some reason there is some thing about us men that think bigger is better! LOL

I also agree at what point do you stop chasing speed. Sometimes breaking a milestone should be good enough. Breaking 100 is awesome, and being able to consistently run OVER 100mph no matter what is the real ticket! I think your a good place to enjoy. If you want to tinker here and there on setup, mostly to make it safer and more stable, then cool. But don't kill yourself over it. You have a sweet boat that runs great.

I wouldn't lower the X dim... I would run bigger diameter and more blades.. if excessive stern lift is a problem... round the ears off to create more bow lift... I'm sure brett BBlades would be very helpful with some recommendations

I have 1/2" spacers on the shelf for sale if anyone needs them.

I was told that the new lowers, 1400's, won't fit the SCX-4's. My friend's 2004 38' has the new 1400's and he only has 9% slip so they must work.
RF said that most Fountains like 16 rake but that was before the SCX. I couldn't tell the difference between 18 and 20 but they also had too much pitch, 38's. I could see a smaller prop working on mine because it's easy to get on plane with a 16.75" that I have. On the other hand, we were thinking slip would go up. Guess I'll just by $100K in props and start testing again.
To the other thread, "what do you invest your money into". Maybe I'll invest into props. They'll go up in value, right? lol

My SCX-4 has the new 1400 lower and I used the older 2 inch spacer , standard SCX,s & -4 lowers will not interchange it has 2 more fasteners & different bolt pattern .

Rob your boat is a full stager? I have the old lowers mine were blueprinted and is a side by side. My slip is only 8%. My propshaft is even with the bottom. when I get to 6000 rpm I've achieved too much stern lift. I can't run any positive trim to carry the bow, the props lose bite. At the boat show I had a long conversation with Brett, His assessment was to also cut the props down and cup the end of the blade he felt the water was shedding of the blade to early and cupping it would give it the additional bite it needed to be able to give it some positive trim. He also felt more rake was in order. My feeling is when these first came out they tried to prop them like a 6, but with the large bullet its hydroplaning the drive causing the exaggerative lift. R lll has had some talk with Wilson on this and they are going to cut down my props, he also said we could try spacing the drive down some. the problem is nobody really knows what this drive likes and it's pretty expensive to keep testing all the theories. not sure why your slip is so high, but my boat has always been between 7-9% even with the bravo's. Wish we were closer I would like to try my blueprinted lowers on your boat to see just how much difference the blueprinting makes.

Mine's a semi stagger. With SC's, -2's and 35P 6bl Herings I still had 15% slip but the boat handled perfect. With the SCX-4's it gets on plane easier and I don't run any trim at speed. Propshaft is parallel to bottom of boat. Any more trim and it just slips. I spent 20 hours blueprinting my lowers, probably took off 5#'s of aluminum, but it'd be nice to try the 1400's. Hurry up and try the smaller props. After your results I'll see if I can get some new props. It's my turn to go shopping anyways because the wife just bought some new shoes. Fair is fair!



Side notes.
My old SC-2's had nickle sized chunks cut out of the leading edge of the skeg from hitting the trailer(bowstop was too far forward the first time loading onto the Myco). NO loss of speed.
My #6 props have several dings and hammer/file marks from me straightening them out and no loss of speed.

I have the 1400 lowers blueprinted, but just on SCX. Around 10% slip.

I don't want to beat a dead horse but what about an arneson?