Direct Drive Question

[Mark308]

Hi all
Apologies if this is a silly question - I am new to this and any help/advice is much appreciated.
I am considering purchasing a speed boat that has a 308 V8 (Australian GM motor) inboard that is direct drive. The boat does not have reverese fitted and I was wondering if this is common and why would they build boats without reverse. I am led to beleive that the boat I am considering was used for racing so perhaps its a weight and or power reason?
Thanks Mark

 

[Bondo]

Re: Direct Drive Question

I am led to beleive that the boat I am considering was used for racing so perhaps its a weight and or power reason?

Ayuh,....... I'd have to Agree,...

A boat without reverse is pretty Useless from the practicality standpoint....

Btw,..... Welcome Aboard to the forums here at iboats.com....

 

[scoutabout]

Re: Direct Drive Question

I've never heard of any regular production boat that didn't have forward, neutral, and reverse. I've got zero experience with racing boats but I suppose it's possible some highly specialized machines might not have reverse.

Whatever the reason you should carefully consider if this is going to be suited (or safe) for your intended application. There's also some other questions you might need to consider such as what kind of fuel does the thing require and is the engine even suited to anything like what you want to use it for.

Sounds intriguing though. Got any pics?

 

[QC]

Re: Direct Drive Question

Fairly common with inboards built for speed. If there is room (there won't be) you could add a 1:1 box and get reverse without changing the propeller and performance . . . However, again, there will probably not be room. If you can get me some pics, I could help. I've recently been forced (self inflicted) to become a pseudo expert in the inboard propulsion department . . .

 

[Mark308]

Re: Direct Drive Question

Hi all
Thanks for the information it is much appreciated. I will send some pics later this week.
Basically the 308 v8 motor is similar to a small block chev (say a 350). They are a reliable and strong motor and this one has been worked (i.e. lumpy cam, holley four barrel, port and polished etc). Our (family) use for it will be mainly for ski, tube and other fun stuff.
It would be good to know about the 1:1 gearbox that may be able to be fitted as I can see it being a real pain launhcing it and than having to turn it around and push it out as it doesen't have reverse. I can also see myself getting wet in the process!
As said earlier I will post some pics later this week. Thanks again for all of the information. This is a great site.
Mark

 

[QC]

Re: Direct Drive Question

The one I have is a Velvet Drive Model 71C 1:1 . It is rated for 310 bhp @ 4200 RPM, your setup should be close to that. Probably higher RPM, but my guess is their biggest concern is the input torque and again, I think you're OK . . . The 72C allows some 400+ bhp.

 

[JCF350]

Re: Direct Drive Question

I am led to beleive that the boat I am considering was used for racing so perhaps its a weight and or power reason?
Thanks Mark

More than likely the boat has/had to much power to use a transmission of reasonable weight. If your going to pleasure boat it you really need to find a different boat. There is a reason some engines/drive trains are called "DOCK BUSTERS".

 

[thurps]

Re: Direct Drive Question

scoutabout; A lot of boats had motors without a reverse. Check out the old Merc dock busters.

 

[JCF350]

Re: Direct Drive Question

scoutabout; A lot of boats had motors without a reverse. Check out the old Merc dock busters.

Those engines did have a reverse function. The engine ran backwards

 

[drewmitch44]

Re: Direct Drive Question

Can ya just add reverse? If ya put the "R" sticker and a knob on the dash maybee that can help. Then just flip the switch to "R". and see what happens. You might have to turn the boat around to go forward in order to back up. If you spin 180 degrees then the bow will be pointing the other way and you can just idle forward a little and you will be going the other way then you were origonally going. I cant spell verry well but i hope you get the idea of what im saying.

 

[steelespike]

Re: Direct Drive Question

scoutabout; A lot of boats had motors without a reverse. Check out the old Merc dock busters.

Merc Dockbusters had reverse By reversing the motor itself Unless properly setup and an experienced operator you ended up busting a dock.It was thought the gearcases of the time couldn't handle the power of the big six.
The two I saw in operation when they were new were pretty much impossible to handle.
As far as the direct drive; check the rotation before pondering any changes.As far as boating activities it is pretty much useless.Keep in mind it is a high performance boat could be run ragged.Check the hull for any problems.

 

[scoutabout]

Re: Direct Drive Question

scoutabout; A lot of boats had motors without a reverse. Check out the old Merc dock busters.

Older outboards, sure -- got a little one from the 1930s myself -- I thought we were talking about inboards though.​

Anyway, Mark, as long as you were going to use it for the intended purpose that's ok. But I would never consider using a powerboat with no reverse for family use, watersports, etc.​

I'm assuming the folks that hang out on this site are of above average in ability with handling boats, trailers, motors, etc., but I know despite my almost flawless abilities with the above bout once a season I'll have a bad day where I need a good healthy (and sometimes foolish-looking) blast of reverse to correct a manouver gone bad -- be it at the dock, ramp, wherever. Somedays the wind and waves are agin ya plain and simple and things go wrong. You say you're new to this game so I'd increase your chances a bunch til your handling learning curve flattens out a bit.​

I'd hate to have no way to stop a boat with kids, family, friends -- heck anybody -- in the water near it. Asking for tragedy is my humble opinion. Even if you can get into neutral ok, a heavy boat will push a kid right under and then the panic starts and it just gets worse. Forget it.​

Get er changed out for a proper tranny or keep that boat for goofing around alone far from shore, swimmers, and other boats.

Do post pics, though cuz it sounds real cool.​

 

[erikgreen]

Re: Direct Drive Question

Can ya just add reverse? If ya put the "R" sticker and a knob on the dash maybee that can help. Then just flip the switch to "R". and see what happens. You might have to turn the boat around to go forward in order to back up. If you spin 180 degrees then the bow will be pointing the other way and you can just idle forward a little and you will be going the other way then you were origonally going. I cant spell verry well but i hope you get the idea of what im saying.

Okay sir, I think you've had enough. Give us the keys to your boat and go hit the couch in the back room for a while

 

[Mark308]

Re: Direct Drive Question

Hi again all.Will post the pics later this week. Just to let you know it does have neutral but I take your points about the risks involved with docks, swimmers etc.
The hull is a saw craft. Not sure if you have/had them there? Its a nice looking hull with a reasonably flat bottom so the wake for skiers is quite minimal (apparantley?).
I do have boating experience but not with a fast boat per se. My last one was a caribeean hull approx 15' built in the late sixties with a johnson 50hp on the back. Its was a good old thing and was powerful enough to get a knee boarder up, providing I kept it light in the hull!!
That said I have never experienced a boat without reverse! Even though it is powerful it can still drive slowly at idle or low revs surely?
Mark

 

[scoutabout]

Re: Direct Drive Question

...Even though it is powerful it can still drive slowly at idle or low revs surely?
Mark

Yup, probably can idle along nice and slow. But sometimes you need to stop RIGHT NOW -- even at idle. Good to hear you've got boating experience though. That's half the battle anyway! Nuff preaching -- I'm starting to sound like my father, and that's just scary.​

 

[mudmagnet63]

Re: Direct Drive Question

makes me think of John Candy in The Great Outdoors when he rents the speed boat

 

[Mark308]

Re: Direct Drive Question

Hi all
Just a quick note to say thanks for your advice, input etc. I bought the boat (couldn't resist) and took it out for the first time over the weekend. It was great fun and does everything I want it to (i.e. skiing, kneeboard, tube etc). Even though it does not have reverse the great thing I found was that when you throttle off it almost dumps itself in the water and ploughs to slow and safe speed almost immediately. I wil post pics later today for all that are interested.
Cheers again.
Mark