Remove cone?

[wettek]

Gidday guys

Years ago, when I was younger and dumber, we coned my dads Evinrude (93) 150 Intruder. It looked cool, heaps more streamlined, so therefore it had to be faster, right? Now that I have done a lot more reading, seems like it may have been the wrong thing to do. It's not a quick boat, only does 58mph, at about 5800, with a slightly tweaked 19" OMC SST. By all accounts, coning this engine may have in fact slowed it down due to the extra drag. Engine is not high, anti-ventilation plate is about 1/2" above the bottom of the hull.
What do you reckon guys, would I benefit by removing the cone and putting the gearbox back to stock? Totally stock engine apart from a set of Boyesen Reeds, which I'm thinking about changing to Chris Carsons.

Hoping for your advice, regards to all

[frederick55]

At those speeds, you're thinking is correct. The cone is more about reducing blowout and adding LWP. It creates more drag as long as it's in the water at any speed. You've got to run it high to see a benefit.

[south599]

agreed.

[wettek]

Thanks guys. You reckon I'll see anything by pulling it off, 100 revs maybe?

[south599]

maybe but you are close to rev limiter so you'll prob have to change props to figure that out.

[wettek]

Any idea what the rev limiter is set at on these engines?

[frederick55]

should be 5800rpm

[wettek]

Thanks for the advice guys.
So, the upshot is that we have probably slowed it down by making it look faster? Would removing it be noticeable do you think? The steering definitely became heavier.

Hope Santa was good to everyone, and the naughty boys got bigger props!

[GregAdams]

The increase in wetted area from the nose cone extension, is probably insignificant compared to the combined wetted area of the boat at 58 mph and the fully submerged gearcase. Unless you are running a lot of positive or negative trim, I doubt you will notice any difference.

[south599]

Thanks for the advice guys.
So, the upshot is that we have probably slowed it down by making it look faster? Would removing it be noticeable do you think? The steering definitely became heavier.

Hope Santa was good to everyone, and the naughty boys got bigger props!

Like stated already you probably wont gain too much by taking it off but id say you might make it to 60.
Also what is your boat and motor combo. There may be the option of actually using the nose cone if it has low water pickup.

[steve@scp]

I've seen those 93 intruder's run over 6k and not hit a limiter.
not sure where the limiter is at. ??

[wired247]

Jack the motor up and take advantage of the cones low water pickups and less drag by getting more of the lower out of the water. Your thinking is kind of backwards.

[wettek]

It's not a performance hull by any means, 16 feet, fairly heavy at 1000 pounds without engine. We use it for skiing. I left the engine the height it is now to make it easier for my dad to drive (he's only got 1 arm) so he didn't have to worry about trimming in and out doing tight skiing turns. I might pull it up a hole and see how it goes though.

[wired247]

With the right prop you should be able to surface the thing and still turn without blowing the prop out. Even a 22-24 pitch chopper or drag prop would be ideal as a surfacing prop you could still ski with. Trim it down for skiing and once you are done skiing level the motor out and drive hard with the prop surfaced and a cowl high rooster tail. The whole point of the low water pickup nosecones is to allow you to raise the motor up as high as possible. You'll go faster, its much easier to steer and you'll get netter mileage or kilometerage as I suppose you say in the rest of the world. Try it. Jack that sucker up high. It makes it MUCH easier to steer up high

Get hydraulic steering for the steering ease . Makes the world of difference.

[south599]

also getting a torque tamer welded onto the skeg helps ease steering a lot.

[GregAdams]

Wettek. What is the hull. I am in Aust. too.

[wettek]

Nothing flash. It's an old Cruise Craft Sabre, just over 15 ft. Very similar to a Haines 1600SO, but a bit beamier, and without
the plank. It's my dad's baby, he loves it as he spent countless hours towing us around when we were kids, and will not part with it.
It would have to easily be 30 years old now.

[GregAdams]

Cruise Craft made a lot of good boats. Jacking the engine to the moon and adding a torque tamer would just wreck a good ski boat. The nose cone won't help or harm your rig. Anything that gets you on the water with your dad is a great boat :) You might try lifting the engine 2 inches at the max so you can run a cav plate extension like the Permatrim brand. That will make it pull skiers a bit better. Then you might be able to run a 21, which will give you a couple of mph, and make it even nicer for your dad to drive. At your current height you would have too much drag from a Permatrim.

[wettek]

Thanks for the positive comments Greg. Do the Permatrims make much of a difference, and are they as good as they are cracked up (and advertised) to be?

[GregAdams]

I wouldn't buy one but that is roughly the shape that would work on your rig. The site says they developed them 15 years ago. But we have been making them for at least 36 years. And we learnt about them from a fisherman who had been doing it long before that with smaller engines. The problem with buying them is that the plate is too thick and strong. If you get airborne at speed you can crack your gearcase cav plate on landing. Especially when your motor is mounted low. Get a good non stretch ski rope around the prop and when it pulls tight against the extension it can crack the gearcase. Seen it happen. Best to make it your self out of 3 mm plate. If it bends or cracks throw it away and make another one. Set up many ski boats, and depending on the type of skiing, raising the motor a little with no set-back and a fitting a plate can be a major improvement.