How do holes in prop hub help performance?

[tomfromblaine]

I've seen a couple of references about holes being drilled in a prop hub leading edge,how does this help? I tore up my hustler prop this weekend and noticed it has holes there, just wondering why before I buy another.

[Surface Tension]

The holes can improve your holeshot by letting exhaust gases ventilate the prop which increases the RPMs out of the hole.

[knoppers]

that sounds risky to me, the prop has a balance, and a cetain RPM it cannot excede. if your looking for a better hole shot, they make different pitch props just for that, which also can change your max RPM's. its best to buy a prop within your spects, and always check with a pro boat mechanic on this. I would not just drill holes in your hub.

they say the fastest prop would be a single blade, but there is no balance, so it would not work.

[Valv]

Knoppers, actually many prop manufacturer already place holes in their props, and high performance shops will drill them. It's a common procedure.

That said it doesn't mean you can get a drill and make your prop look like swiss cheese, you have to know where and how.

[Whoaru99]

I've even seen some ventilated props that come with plastic plugs having different sized holes so the amount of ventilation can be tuned.

I agree with your suggestion of not drilling holes on your own - although I would not be afraid to let someone who knows exactly what they are doing have at it.

Not sure there would be much benefit on "standard" props, but those S.S. props with lots of cup, rake, etc. really bite and can benefit from the holes.

For anyone who wants to know all about prop theory, design, performance, etc., Mercury has a book titled "Everything you need to know about propellers." It's not an engineering level design book, but from a consumer prospective, probably is "Everything you need to know..." The P/N of the book is 90-86144-92. It's softcover and about 55 pages, don't remember the cost.

PS: The Merc prop book supports your statement about the single blade prop - most efficient design, but vibration is a problem.

[Surface Tension]

Vented props won't increase your RPMs at WOT, only at the time of your hole shot.

Lets say your RPMs at WOT are within the recommended range but your hole shot could improve, a vented prop may be the answer. Venting isn't a replacement for common steps to get your boats on plane faster like trimming in, weight placement, transom height and trim tabs.

Most Thru-Hub exhaust props can be vented, There are diagrams with instructions on how to do this properly and balance isn't an issue when done right. Its also a process with small adjustments in hole size. I think most prop shops could do this for you.

[Northlander]

Jay Soderbloom is doing just this to one of my Satinless props. I cant wait to see how she runs with a bit of cupping, pitching and holes. Its either going to fly or be like dragging my 28# anchor.

[Valv]

Northlander, wow, that Satinless must be a special prop on that Yamaha.

You people up north get all the goodies.....

Sorry I couldn't resist.....

[Scoot]

Valv,

You shouldn't tease- I've heard removing the satin from the props results in a dramatic performance increase!

Tough crowd around here, eh Northlander?!? I'm sure you can't wait until Valv or I have a typo next- you'll jump on us like a fat kid pounces on a Snickers! Oh well, I can dish it out so I better be able to take it too!

[Surface Tension]

We run the H E double hockey sticks out of out props up here.

[Valv]

Scoot,

I did a search but couldn't find it. Do you remember the " Hugh crappie" post that came up many years ago ??? That was a classic....talking about having fun at the expenses of a small little spelling mistake.

Northlander, I hope you can take a little "picking on you"

I know I will have one coming soon, now....

[tomfromblaine]

Where is Jay located? I'm going to satinless no for real, I'm switching over as soon as I finish this side job

but I need to replace this Turning Point before the weekend though.

P.S. thanks for the info.

[Northlander]

Dont worry Valv I have thick skin. For as much dump as I dish out I get double back. Now that I have th new boat and ride in a Ranger often I find myself playing little prop games just like the Ranger Boys do. I really dont care how fast I go empty but when Im full and running in a tourney or league I would like a couple more miles per hour. I think I can do it cuzz Im well in my RPM range. Ill let ya know how that new prop works.

S.T. is right the waters in this neck of the woods can be a motors worst nightmare.

[Northlander]

Tom you can get a hold of Jay at www.soderbloom.com

[tomfromblaine]

Thanks Northlander, I'll be in touch with him asap.