Prop venting

[marada1]

I know there are some threads about this but I was hoping for some specific advise from any experts on the matter. I want to drill vents in my prop in hopes of improving my hole shot. Boat is a 18ft I/O about 230hp (apprx. 2700 lbs). Running a Solas aluminum (Amita 3) three blade 21. WOT is 4500 @ 51mph. Hole shot is a little sluggish. I have the same prop in a 19 but there is too much potential for an over-rev with the wrong driver, plus I don't want to give up my top end.
I've seen the diagram as far as where to drill but I can't seem to find it again. Also,what size holes are recommended? Can I expect a noticable improvement by doing this?
Thanks in advance

 

[gcboat]

Re: Prop venting

http://s36.photobucket.com/albums/e43/cmarques1/prop vent holes/

 

[stevens]

Re: Prop venting

http://www.marinemechanic.com/site/page76.html

 

[marada1]

Re: Prop venting

Thanks for the links. Any thoughts on this being worthwhile in my stiuation?

 

[marada1]

Re: Prop venting

OK, I drilled the 7/32" holes. Seemed to help somewhat. I'm think'in I'll drill them to 1/4". Any thoughts on how big I can go?
Thanks

 

[TomP]

Re: Prop venting

I have heard that you should probably stop at 3/8. Can you explain how you drilled the holes as I am thinking about doing this too.

 

[marada1]

Re: Prop venting

Center punched then used a cordless drill. I'm working on an aluminum prop so it's pretty easy drilling.

 

[wca_tim]

Re: Prop venting

If I were you, I would think hard about looking for a decent laser 2 that is already vented. A newer one would have the replaceable plastic inserts that you can buy different diameter holes for a song. I think it would be really hard to get the kind of benefit you're looking for the way you're doing it. The stainless prop would also really help with your hole shot. Not sure if you would want a 21 or a 23... probably a 21 (note that since it is cupped and stainless it will bite better than your current prop and probably give you a little lower slip numbers and due to the cupping act more like a 22.). They'er common enough props that you might find one for sale (that you could try out) at a local shop.

Just some thoughts. If you lived closer, I would let you try a 23 laser 2 to see how it works. I've got a couple of them.

I also really like the solas 4-blade titan i bought... and it came out of the hole like a train...

 

[marada1]

Re: Prop venting

Hey Tim,
I'm a little afraid of wrecking my Cobra drive with a SS. "Back in the Day" when I was running fish & ski's and outboards, SS was all I would run. Now I mainly just use my boat for family outings (skiing, boarding etc.). However, I do like performance (it's in my blood) and thats why I did the Vortec / Edelbrock upgrade. I'm pretty pleased with the result. 50 mph aint too bad for a (fairly heavy) 18ft I/O with a V6 & 3 blade aluminum prop. Just try'in to get all I can with what I've got and improve the hole shot a little.
Just a couple of weeks ago I went to a nearby lake I've been to hundreds of times. Didn't put in at my usual ramp but a ramp I had used some. Just 15 or 20 ft from the ramp I found what must have been a chunk of concrete. Bent one blade and knocked a chunk out of another. Don't know what would have happened with a SS prop. Bent propshaft, busted gear? Anyway, ordered a new Solas 21 Amita. Straightened out the bent blade, and I'm still running the damaged prop. Doing the vent testing on it. When I find what hole size is best, I'll drill the new one and try it. Heck, I might pick up a little more speed with 3 good blades!
If I was your neighbor I probably wouldn't be able to resist the urge to try your Lazer. But right now I can resist the $$$ to buy one.

 

[wca_tim]

Re: Prop venting

Were the ss props your talking about back in the day solid hub props? The stuff I've broken with them was with a solid hub set-up... but I hear you... and I am happy with the solas titan 4 I bought last year... quality prop for really reasonable money...

 

[wca_tim]

Re: Prop venting

Were the ss props your talking about back in the day solid hub props? The stuff I've broken with them was with a solid hub set-up... but I hear you... and I am happy with the solas titan 4 I bought last year... quality prop for really reasonable money...

 

[marada1]

Re: Prop venting

Not sure what you mean by solid hub. Have hub designs changed alot in the last 20 yrs? So how much do you lose on the top end with the Titan 4?

 

[wca_tim]

Re: Prop venting

Not sure what you mean by solid hub. Have hub designs changed alot in the last 20 yrs? So how much do you lose on the top end with the Titan 4?

A lot of the newer hub assemblies will theroetically spin the hub instead of breaking the drive and take some stress off the drive... with stainless or aluminum. more of the older hub set-ups are much more solid and don't give.. transmitting a lot more to the drive.

On the solas titan 4, I bought a 21 because everyone said i would lose rpms and a 23 3 blade was working best for me for all around with that engine. It would up being a great prop to pull skiers and so forth and is the smoothest running prop I have. A 23 might have been better for al around performance, but the 21 solas 4-blade came out of the hole like a drag car on hot slicks... forget to trim it in and it would damn near stand the boat up. In that sutuation, I would reel it in before the rpm's went over 4900 or so... and that was at about 50 mph. The 23" laser 2 was the best for all around performance and it would get me 55-57 on a good day with a light load... Hope that helps...