Surface drive, "traditional" drive, or stay with jet?
 

Let me first start off by saying you could fill a thimble with my knowledge of outdrives/props and still have room left over. I also don't really have any "boating buddies" so everything I think I "know" about outdrives is what I've heard/read - and we all know how credible that is...

I realize my boat is a lot smaller than what most of you probably deal with, but I didn't know where else to ask a surface drive question.

The boat:
21' Liberator (21' Daytona splash with more freeboard)
383 aluminum LS1 w/ closed cooling - 550hp @ 5900 rpm / 500 trq @ 5000 rpm
Dominator jet

I am looking to go to an outdrive basically to increase the speed of the boat without more power. However, triple digit speed is the goal...so if 550 hp doesn't get me there I will increase power. However, with a BBC and a Bravo XR my hull should be mid/high 90's to low 100's with 650 hp; my engine is almost 300 lbs lighter than a BBC.

I've been used to a jet, so I really have no idea how to "treat" an outdrive (Bravo XR or surface) to get them to last. I will say, I have also become very used to going in quite shallow water; so with an XR style that's a habit I'd need to break...

Here's my questions about the Arneson:
1) How well does a single Arneson work on a smaller boat like mine?
2) I've heard about planing issues - is this going to be an issue with a tunnel hull cat?
3) The manufacturer of my boat says he's set 4 surface drive boats up in the past - and while they've all been fast, none retain their surface drive today - any reason the owners would dislike them?
4) Other than cost, is there any reason NOT to do a surface drive with a single engine boat of my size?
5) I hear about dock handling - could it really be any more difficult than a non-rudder jet at idle speed?

Here's my questions about the XR style drive:
1) In all probability if I'm used to driving a jet, I'm probably going to break an XR, aren't I?
2) Is there any reason (other than cost) to pick this over an Arneson?

General questions:
1) With either, how do they actually "attach" to the engine? I'm guessing it's not like the PTO with spicer driveline I have now?
2) What ratio would I want with my engine RPM?
3) Realistically - would I be better off to stay with the jet and increase power to hit triple digits and/or start with a boat that already has an outdrive?


Thanks!
Zach

Hey FormulaZR, what's up. How's your setup running right now? I will preface by saying that I've never been in, or run an Arneson equipped boat, but I have had a single outboard, single sterndrive, and a jet. The jet is in my opinion the most maneuverable of the 3. It's kinda nice having infinite control over forward and reverse, and being able to throw it back and forth while docking. However, having an actual NEUTRAL position on the outboard/IO is sure a nice thing. If you are used to the holeshot of your jet, you will not get that same holeshot with a sterndrive.

That's about all I have to add...but I think a surface drive LSx picklefork would make my pants dance. Keep us in the loop on what you do. (And find somebody to buy my jet :lolhit:)

Wow, I just run into you everywhere, don't I?

The boat is currently running pretty good, I think. I'm seeing an honest 68-70 out of it with 4 people, full fuel, and loaded cooler. I was going to run it this weekend with just me and a light fuel load - but broke the steering cable; so that didn't happen.

I want to go faster than that, though. And you know I can drop the compression and TT the LS; but I'm hoping to increase speed without burning 2x fuel. I am concerned about running "deeper" with an outdrive and about all I hear about how they don't like snap throttle input. I do like the somewhat "bulletproof" nature of the jet. I can destory an anvil with a rubber mallet - which is why I'm real hesitant to go to an XR style drive.

I agree that docking and slow speed manuvering in a jet is really nice; as long as you don't need to do anything in a hurry.

I've also considered jumping ship and going to a outboard tunnel hull - but I'm real unsure of them because I have zero experience with them.


I'm really leaned toward a surface drive, it seems offer the best durability, highest speed, and shallow running...and the cons I *think* I addressed in my first post.


Did Adam not buy your boat? I was sure he would, especially after your price drop...

He was real interested, but I haven't heard a peep out of him for a few weeks now?

What kind of rpm are you currently turning with your setup? What cut is your impeller...ss or alum? I am just under 70 mph with my setup, but that is only at about 4800 rpm...I know my motor has a LOT more than that in it, but the pump needs to be worked to take advantage of the rpm capability of the engine.

You might have a lot of speed hiding in your pump yet, if it's relatively stock. Loaders, ride plates, bowl stuffers, etc. GOOD LUCK!

Hmm...hopefully he'll call back and buy it. Sure is a lot of boat for the money.

Right now I've got an aluminum B in it, turning 5800-5900 rpm. The pump has loader, rideplate, diverter, droop, and shoe. The problem is it's a heavy jet boat and it has a lot of people in it. I am anxious to see how to does with just me; hope the new cable gets here quick. I would like to go an AB and get the revs down some, though. Also, the shoe is the wrong type for this hull and has too big of a mouth opening - so there may be a few mph there...still won't be 90, though.

In terms of efficiency, the prop boats are the fastest. Never seen a jet and prop boat with equal power, and the jet boat being the fastest.

On a boat like yours, with the power you have, a XR should live fine. You can always upgrade to an IMCO ect.

If you want info on the Arnies, which is the coolest drive in town, in my opp. contack Rik on the board. He's with Arneson, and know everything there is to know about surface drives.

Good luck with it.

Sounds like a cool boat. But instead of doing the work to convert to a surface drive why not just re-rig the boat with a single outboard? I have a 21 Liberator (bass boat style) and it runs well into the 90's with a 250 Mercury.

No doubt a prop will out run a jet everytime with similar power and hull/weight. I'm absolutely not trying to argue that; and that is why I'm considering a change over to an outdrive.

I'm concerned with XR reliability because it seems like some guys back up 750 hp motors with them safely and others grenade them with 500 hp motors...so I've got to assume a lot of that is the operator. Unfortunately I don't know the "proper" way to drive an outdrive; so I'd probably be the guy who blew them up with 500 hp...



That is also a possibility.

I will probably not convert my boat for several reasons. 1) Cost; 2) The transom of a non-O/B Liberator is not designed to hold an O/B - it would require quite a bit of transom work; which also goes back to reason #1.

But, I would consider going to a 21' Liberator with a 300 hp O/B.

My Idea...
 

I think I would look at a Blackhawk drive...
I would think with a light weight boat like a 21 lib it would live fine behind that power.
You get a surfacing drive with dual props to counteract any prop walk.
Just my 2 cents...

That would be your best bet. Or if you wanted more speed set one up with twins and your running 120mph plus and it would have acceleration like a drag car.