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View Full Version : To Lab or not to Lab



jasonkennedy
02-23-2012, 04:05 PM
Hey guys




,70208I currently have a 1994 sweet 16,The boat has a 5.0 merc with through hull exhaust, i am considering sending the prop out to have it labbed , my question to you guys is do you think it is worth it ? the place that i spoke with says @4600 rpm 58mph i have around 4% slip,If they go ahead and lab it the prop should turn about 300ish more rpm and give me 3.5 mph on paper but with additional slip possible i may only get 2mph. what is your opinion of a few small mods to squeeze a few mph out of this particular boat ? i know the 1000.00 per mph rule and i know an alpha ss works well on this boat as well . Any ideas?

jasonkennedy
02-23-2012, 08:32 PM
My prop is a 21X13 7/8 lazer , i was going to have brett from bblades propellor do it http://www.bblades.com/

jasonkennedy
02-23-2012, 10:24 PM
320.00

BUIZILLA
02-25-2012, 08:32 AM
labbing a Lazer?

REALLY?

jasonkennedy
02-25-2012, 11:53 AM
what prop would you recommend and why wouldn't you lab a lazer

jasonkennedy
02-25-2012, 03:52 PM
buizilla ? info on this please ?

BUIZILLA
02-25-2012, 08:02 PM
I guess I'm having trouble with the 4% slip on a box stock lazer your starting with, and you have been told they can better that?

uhhhhhhhh

no

The Hedgehog
02-26-2012, 09:58 AM
I think you would be wasting 320 dollars. If you want to go faster it needs more power. You will likely lose 3 mph of cruise.

That hull loves a Ss. That could be another route. If you are dong that, you need to Waite and re-prop it anyway.

jasonkennedy
02-26-2012, 01:38 PM
70244

BUIZILLA
02-26-2012, 02:49 PM
computing it with a 1.65 makes it a negative number, -.048, or less slip than bite, totally impossible

even 5% is almost unbelievable to be improved on.....

http://www.rbbi.com/folders/prop/propcalc.htm

jasonkennedy
02-26-2012, 02:56 PM
So...
what are you guys thinking ? leave the prop alone and search for an alpha ss ? And where can you find an alpha ss now a days?

Ghost
02-26-2012, 05:19 PM
Is it common for labbing to INCREASE slip? I'd have thought it was intended to reduce it a little. And so, for clarity, do I understand correctly that the prop guy says he will likely make your slip % increase (bad), but that thinning the blades will cut resistance and you'll turn more RPMs (good), and the net result will be a slight gain?

I can imagine this in theory. If you had a prop with blades that were 3 inches thick, even at zero slip (hah), it'd be so much metal to twist through the water that you'd be very slow, with full power not getting much RPM at all. If you labbed it down to normal blade thickness, odds are your slip would end up above zero but the prop would be thin enough to turn at real RPM. Slip would have increased a bit, RPM would have increased a ton, and speed would have gone up nicely.

But with that said, your prop isn't ridiculously thick and your 5% slip sounds great. Like, as good as or better than any I've ever heard of. Wouldn't change that prop, I'd covet it. I'd leave it beefy and look at adding adding power. Unless you can borrow another one and confirm that any other stock 21 Laser will do as well right off the shelf. In which case, experimenting won't kill the only golden goose.

seabuddy
02-29-2012, 06:11 PM
This is interesting. How about a more complete expaination of a Ss?

gcarter
02-29-2012, 07:05 PM
An Alpha SS wa a very limited production (very) short outdrive that was originally based on an outboard lower and a special short Alpha upper.
They haven't been built in a couple of decades (I think) and parts have been gone for years.
They seemed to work well on some hulls and not much improvement on others.

jasonkennedy
02-29-2012, 11:22 PM
could the fact that the niagara river has a running current of about 4 mph where i was running and i was running with the current skew those numbers a bit ? (BTW this boat did show 64 one day this season in ideal running conditions on gps) thats not bad for 220 hp (i think) stock 5.0

After thinking about the whole idea of a performance boost for the boat and the fact that there are boats here in my back yard running close to 170 mph i think i am going to to enjoy the boat for what it is and leave it alone. I have family members/neighbors that got caught up in the (mile per hour) game in the past and never really seemed to get anywhere but just told taller tales (after spending boat-loads of money). If i do anything in the future it would be a 5.7 vortec or a 383 ...hence go big or go home...(kinda)

You would think i would have learned my lesson about trying to go faster in a boat , I was helping one of my neighbors for weeks dial in a drag boat (berkley driven pickle-fork) and they wrecked it 20 seconds after i got out of it, suggesting he take one of our neighbors for a ride (pump grate screws walked out creating a drop down brake throwing them in the water @95mph after 360ing the boat(injuries but not fatalities)

Btw thanks for all of the input guys

this is just a video i shot on the boat not the accident


http://www.youtube.com/watch?v=pER-cZ58GY8&list=UUlEpt-49p1lAYy90YlMktiQ&index=40&feature=plcp

Carl C
03-01-2012, 08:24 AM
The current definitely raised your top speed. It always does mine on the St. Clair or Detroit Rivers.

zelatore
03-01-2012, 11:17 AM
Like Carl said, if you were running down-river and using a GPS speedo (it sounds like yes to both) then absolutely the current boosted your speed. I don't have the calculator handy, but just deduct the (estimated) river current from your recorded top speed and run the numbers again for a truer slip number.

tmdog
03-01-2012, 11:37 AM
did a little thinking
could the fact that the niagara river has a running current of about 4 mph where i was running and i was running with the current skew those numbers a bit ? (BTW this boat did show 64 one day this season in ideal running conditions on gps) thats not bad for 220 hp (i think) stock 5.0

After thinking about the whole idea of a performance boost for the boat and the fact that there are boats here in my back yard running close to 170 mph i think i am going to to enjoy the boat for what it is and leave it alone. I have family members/neighbors that got caught up in the (mile per hour) game in the past and never really seemed to get anywhere but just told taller tales (after spending boat-loads of money). If i do anything in the future it would be a 5.7 vortec or a 383 ...hence go big or go home...(kinda)

You would think i would have learned my lesson about trying to go faster in a boat , I was helping one of my neighbors for weeks dial in a drag boat (berkley driven pickle-fork) and they wrecked it 20 seconds after i got out of it, suggesting he take one of our neighbors for a ride (pump grate screws walked out creating a drop down brake throwing them in the water @95mph after 360ing the boat(injuries but not fatalities)

Btw thanks for all of the input guys

Jason- - I applaud you on your decision. Enjoy your boat as is, providing it is mechanically sound. I spent a ton of money chasing those elusive numbers to achieve a 80mph 18. Was it worth it-------NO.

JimG
03-01-2012, 12:25 PM
+1, Enjoy your boat, you have a great one!!

Kirbyvv
03-02-2012, 10:06 AM
I think your boat is running very well the way it is. A friend of mine had a 16 with a 5.0 and could only get about 53 mph out of it.