Very sensitive planning pads / and slime

[cyclops]

Cute syndrome of my boats planning pad and slime. Boat out of storage does 54 mph at a rev limit of 4900 rpm. 6 months later it only does 48 mph at 4800 rpm and can not reach the revlimiter. Can a boat and drive be factory setup that close to cavitation, so a 1/2" of the soft green slime causes cavitation and that much difference?

[Corpus Skipper]

Probably not cavitation so much as the drag caused by the slime.

[Sean Herron]

Hello...

Small solids into the prop wash...

What...

Sounds crazy - but at a bazillion RPM who knows what the F'un sunny day is going on... :)

The 'good old boy' answer is yup...

SH.

[yipster]

not beeing "cavitation" implosions at the prop i belive we talk "ventilation" or even another named fenomenen...

[RANCHI OTTO]

I don't know if you have tested the boat on the same way, because I've noted that the planing boat go faster in shallow water, opposite for semidisplacement or displacement boats, they go slower.

The drop in speed is of 11 % and the revolutions loss only 2%.
The propeller absorbs the less power at same rpm.
Control the blades of the propeller, perhaps one has taken a blow.

RANCHI OTTO

[cyclops]

Thanks Ranchi. The Prop Shop owner is doing a full blown base line check and power runs, clean and then when I get down to the 40's. I always run the WOT in the same place at sundown calm.--------------------------------------------------- At the " clean 54 mph conditions" I can not cause a prop " blow out " under any condition. At the " slimy 48 mph condition" I blow the prop out at any speed from dead slow, to 40 mph, just by applying a very fast full power.-----------------------I think I am doing some snorkeling this summer

[artemis]

Cute syndrome of my boats planning pad and slime. Boat out of storage does 54 mph at a rev limit of 4900 rpm. 6 months later it only does 48 mph at 4800 rpm and can not reach the revlimiter. Can a boat and drive be factory setup that close to cavitation, so a 1/2" of the soft green slime causes cavitation and that much difference?
Suggest you haul her and clean the 1/2" of gunk off the bottom.
The "softness" of the slime and the surface irregularies could easily account for a 6mph drop in speed (and I wonder how much that slime weighs?)

[cyclops]

Everybody: I remember reading of a very slick coating the Offshore boys use on the bottoms. Something spelled like K.I.S.S. a organic coating that is super slippery. Do you know the name of it?

[yipster]

did read about it but cant come up with a name. it was a messy sort of low cost cowfat thing, better use speedo anti fouling.

I've noted that the planing boat go faster in shallow water
i lost some rpm in deep seawater, thought it was the salt or temperature but shallow vs deep water is most likely the scientific reason.

[artemis]

Boat out of storage does 54 mph at a rev limit of 4900 rpm. 6 months later it only does 48 mph at 4800 rpm and can not reach the revlimiter.
What is the weight of the "gear" (food, bedding, clothes, tools, odds 'n ends) that you take out of her before storage. What is the weight of the gear put aboard at time you take her out of storage. You'd be amazed at how much "stuff" accumulates in 6 months of cruising - and it all weighs! :)

[Corpus Skipper]

I think I am doing some snorkeling this summer Now you're cookin' :D You'd be amazed at how much "stuff" accumulates in 6 months of cruising - and it all weighs! Ditto on that. I just emptied out my 26' Chris Craft after hauling her out for the year (gas prices :eek: ). It took me nearly 3 hours to get the stuff out and sort it (there's that %#@!! chart! :D ). Probably around 400-500 lbs. worth.

[cyclops]

I remove or add nothing, except myself. Always stored with a full tank of gas.

[RANCHI OTTO]

How much did you have eaten in the last 6 months ?
What about your actual weight ? Always the same ?

RANCHI Otto