Nose Cone and Slippage

[metraman]

I think I'm closing in on my slippage problem and would like some constructive input. I checked my tach 5000 RPM I now have a Mirage Plus 27P unaltered boat runs 73.5 GPS 15% slip 22' Classic. This boat came with this cone does anyone think this could it be my slip problem? It doesn't look like it's welded on if it needed to come off will heat do it?

[Pismo]

That is a high slip number. Is that a piece of duct tape on your drive? What condition is the bottom of your boat? Have you weighed it lately to see if it has water on board. I don't think the nose cones alone could explain any/all of your problem. I believe and have read that a MPlus prop acts like slightly more pitch than stated on the prop, ie a 25 is actually more like a 25.5 or 26. With my 25" MPlus I get far more believable numbers if I assume 25.5" pitch, then I hit the 8-10% slip area. Excess weight, running surface condition, excessive drive drag, tabs stuck down(I doubt), bottom hook, all things to consider. If accurate tach and GPS speeds, 8-10% slip at 5000rpm with 27.5" MPlus prop and 1.5 drive yields high 70s. Try a run at exactly 4000rpm and see what you get there.

Best,

[metraman]

I had the boat out yesterday at 3500 it was 50.5 mph the labbed 25 vector I took off was 48.5. I took the prop off tonight and plan to have a good look at the bottom tomorrow and maybe take the cone off. If that doesn't help I will take it to the scales. The bottom looks good of course I don't know what to look for as far as hook. Do these hulls hold water in the core there's nothing in the bildge. Thanks

[Chili 18]

At speed, the drive leg is like an aircraft wing. Needs to be S M O O T H. Any disturbances will disrupt hydrodynamics and could be causing air or 'bad' water to enter your prop. Remove the nosecone using a rubber mallet. Usually does the trick. Sand the whole thing smooth and re-afix the cone making sure it is straight... using Marine Tex or JB weld to glue it on and later to fair the surface S M O O T HHHHHHH.. Fill and sand primer to take out the last tics, Some good two part epoxy or suitable drive paint... And you're ready to try new props knowing that they have a fair oportunity to be their best...

Rotsa Ruck...

C

[metraman]

I took the cone off and ran it last night 4000 RPM nets 57.5 MPH.I plant to add some jet my plugs are still white. I think my next stop will be to the scales to see how heavy it is. The 27P wants to blow out on hard turns the 25 Vector didn't do that.
Thanks

[Lenny]

BTW, I use an underwater writing slate for speed runs.. The pencil is attached with a rubber cord, and it is much easier to handle than paper.....

Are you using tanks when you do this or just a snorkel :tongue:

[Rootsy]

Are you using tanks when you do this or just a snorkel :tongue:

I was wondering what brand of flipper gave the lowest slip numbers... :biggrin:

[Pismo]

4000rpm with a 25" MPLus in a 22 with a 1.5 drive should yield about 60mph so you are close.

[metraman]

57.9 at 4000 RPM 27P Mirage it feels like it was draging a anchor it was very warm last night a calm.The 27 was only 1 1/2 MPH faster than the Vector 25 labbed. I must have some extra weight only had 1/2 tank of gas.

Thanks for your input