Pvs vent holes on props ??? I don’t get it.

[QBhoy]

Ok
so I've had a few beers, but please and honest to god...someone tell me they have had a useful result out of the pvs vent hole idea !!
someone tell me I’m wrong I’m thinking these are just a poor excuse for not getting your boat propped right ??
Ill go so far as to say they are as lazy as an add on doel fin or hydrofoil stupid thing on the drive ?
apologies if I’m missing the point but having recently propped a few of my boats pretty well (long story) and loads of friends boats...I haven’t once found that the varying increments of pvs holes have made a single difference to the advantage.
3 particular recent tests with only the first stage and smallest holes to the plugs have all been terribly horrible on test. Like a manual gearbox car with a clutch slipping and not engaging efficiently until well over the cruise rpm...the result of which is a complete waste of fuel over the season. The vent holes don’t seal until way up the revs and generally don’t give anything like the grip of a closed vent plug acceleration, when you get the pitch suited to the boat in general.
Total lazy cop out.
Maybe we don’t have the right boats to take advantage of it fully here ?? All I can think of. Mayne the bass boats really benifit. God knows how ?? Totally don’t get it at all
to bore you a little more, on one recent test we did with a Mariah 18sx..3.0 merc and alpha drive. We had a 21” laser 2 on her (after knocking out a wedge in the trim anode fin), we left the medium holes pvs plugs in...she wouldn’t stay on the plane at anything under 3600 rpm...and a little after she seemed to seal the vents to a decent top speed of around 42/43 mph at 4850 rpm. Fair play.
But with the full non vented plugs in...my god. She gripped an bit straight away and would sit on plane at 3200 rpm at the same or similar speed. No sign of slipping or venting.
This example is on the low side of power to weight ratios...so I ask again. What’s the point ? Why not just get a properly suited prop in the first place ??
only exception or excuse I’ll make for myself is not having any experience with bass boats. Is it only them that need it ?? Surely not ? Surely lightweight boats and ridiculous hulls with high HP don’t need a vented prop ??
some one please tell me what they are for ??
rant over, haha.

 

[JFZ]

I have some experience with them on a multi species boat and I agree.

 

[Scott06]

Ive found good results on three different props allowing the engine to get into its power band sooner from a dead stop by venting a little .

Found medium plugs worked best with my vensura , on the Revolution 4 with more bite to the water two large and two medium plugs worked best ( all large plugs was too much slip). Found with no vent the rev 4 it took longer to get rpms up to 2800, just played with different plug sizes by seat of pants feel. I think it really depends on the boat engine prop combo wether it makes a difference.

In my case I got better top end and much less slip with th Rev 4, but hole shot was better with the vensura that had less cup and smaller blade area. Venting the rev4 a bit got some of the holeshot back by allowing it to spin up quicker. If I had a 5.7 vs. 5.0 probably be able to overcome the grip of a bigger prop with bite... making th plugs unneeded

 

[dingbat]

Ran a vented-prop (Stiletto) in my last Grady with good results.

Noticeably improved the low end throttle response for running the inlet without giving up my cruise speed which is the primary concern when running great distances

 

[jimmbo]

Venting helps very much with engine that have very good High Rpm power, but are a bit weak in the lower Rpm range. Examples are the Inline 6 Merc 150hp, and the OMC 49 cu" 75hp.
I still use a vented prop on my I/O and it has great acceleration. The prop used was RAKER, the Vents are drilled and not adjustable. I use a slightly smaller vent on my Enertia
https://www.youtube.com/watch?v=VepbXm5RFDI

 

[QBhoy]

Ok so of use to some then. I suppose if you need better out the hole for a reason they might make sense but they seem to always compromise cruising until you are at a speed more than what you would consider cruising. I’d personally maybe prefer just to have a prop for all round and a prop for hole shot...should I need it.
Its a horrible feeling too, if nothing else. Maybe it’s the engineer in me that hates the inefficiency of it all.

 

[dingbat]

I’d personally maybe prefer just to have a prop for all round and a prop for hole shot...should I need it.

What about the vast majority of us that don’t do water sports but need the throttle response in hairy situations?

Typical day....3 people, 147 gallons of fuel heading 40 to 90 miles offshore for the day.

Between me and offshore is 5 miles of very tricky, nasty water with a standing wave marking the location of the outer bar. It’s a go, no go decision at that point. No turning back once past the bar. From there we have 2-3 hours each way to the fishing grounds.

This is the exact scenario the Enertia Eco was designed to address. Vent for low end, cruise with efficiency

 

[QBhoy]

What about the vast majority of us that don’t do water sports but need the throttle response in hairy situations?

Typical day....3 people, 147 gallons of fuel heading 40 to 90 miles offshore for the day.

Between me and offshore is 5 miles of very tricky, nasty water with a standing wave marking the location of the outer bar. It’s a go, no go decision at that point. No turning back once past the bar. From there we have 2-3 hours each way to the fishing grounds.

This is the exact scenario the Enertia Eco was designed to address. Vent for low end, cruise with efficiency

I’d just get a prop that suits the boat and motor in first place. Never found a need to have the vents open yet. Horrible feeling. And recommend that everyone should at least see what it’s like with them closed. Transforms the way a well suited prop will pull.

 

[QBhoy]

And there is nothing efficient about venting when cruising. Literally nothing.

 

[jimmbo]

At cruising speeds, which I will assume the boat is planing, the vents are usually closed. They may reopen briefly when exhaust pressure increases immediately after additional Throttle is applied, but will close again as the volume of water flowing over them increases

 

[QBhoy]

At cruising speeds, which I will assume the boat is planing, the vents are usually closed. They may reopen briefly when exhaust pressure increases immediately after additional Throttle is applied, but will close again as the volume of water flowing over them increases

This may be true for some Jiimbo. But in the dozen or so times I’ve tried vented with mine or other boats. The seal tends to happen above the ideal cruise speed. Recently on a Maria 18 sx with 3.0 and 21” laser. We had the medium holes. It wouldn't stop venting till 4000 rpm or close to. This was about early 20’s cruise speed. We put the full non vented plugs in and it would sit cruising at the same speed at about 3300 or maybe just less.

 

[porscheguy]

I’ve felt no discernible benefit from having plugs open or closed with one exception. My quicksilver lightspeed which is a laser2 with small, square vents (for which there are no plugs made) performed horribly with the vents wide open. My only recourse was to fill them with JBweld. Vast improvement.

Althoughi dont experience any benefit, I also understand that other boats and props may gain something. I don’t think they do any harm to be there closed up.

 

[QBhoy]

I’ve felt no discernible benefit from having plugs open or closed with one exception. My quicksilver lightspeed which is a laser2 with small, square vents (for which there are no plugs made) performed horribly with the vents wide open. My only recourse was to fill them with JBweld. Vast improvement.

Althoughi dont experience any benefit, I also understand that other boats and props may gain something. I don’t think they do any harm to be there closed up.

Most pvs props wouldn’t have the holes full bore open I’d think. Like this they are all horrendous things. Even with the small hole plugs, I find them useless on all I’ve tried. Racking my brain I could maybe only understand it on a 80 mph bass boat with a silly high pitch like a 30” or something. These could take advantage of be high pitch at speed, and I can only assume the vents help with the draw back of out the hole performance this would see normally. On a normal boat...I really don’t get it. I imagine that those who think they are of use, mayne haven’t tried it with the vents closed with plugs.

 

[jimmbo]

My Enertia came with the holes blocked. When I had borrowed the prop from dealer(off his personal boat) I noticed it was a little slower out of the hole than my RAKER, but outperformed it in every other way. So when I ordered my prop, I also ordered the PVS plug kit. A couple of trials later and the Enertia was better than the RAKER in hole-shot. While there is some slip at non planing speeds, it has never bothered me. One, the engine less loaded. Two, I spend very little time running between 10 mph and 20 mph. Once on plane, this prop has a very good grip on the water above 20 mph(about 2000 rpm) as the vents are closed.
Nice thing is, Mercury’s PVS System allows you to choose if you want to take advantage of it, or not to.

 

[Texasmark]

It's 2 props in one; one high pitch, the other lower pitched. Venting exhaust gasses across the blade decreases the density of the medium and allows the engine to rev faster like a low pitched prop would do. But at high speed you don't want a low pitched prop. You want a high pitched prop...for boats powered adequately. So punch the holes and enjoy the ride. They work....but you need to get the diameter right to suit your setup. To large a hole and your rpms will rise too high in the hole shot and thrust will be limited in doing so. Too small and they are not much good.

 

[QBhoy]

Totally get that for bass boats.
But generally they are still venting at low planing speeds compared to filled. It’s never been good on any of the applications I’ve tried or friends have tried. Maybe I’m just too fussy over getting the right prop in the first place. Who knows.

 

[Scott Danforth]

drink more beer...... you get less fussy

 

[Texasmark]

I ran ports when I had a pad hull, bass boat. My current boat is a 2002 1750 Crestliner Fish Hawk and after buying a TP Hustler ported, found that I too did best, with this boat and it's intended use, after plugging them. Reason being, I wasn't interested in hole shots and WOT MPH and I had to run this new one to realize that. I am more interested in mid rpms, cruising if you will, with this boat and the holes for that are a nuisance. But I am enjoying the rake and cupping assets doing what they were designed to do........and Crestliner's reverse chines.....really an asset for fast planing and a dry ride.

 

[QBhoy]

I ran ports when I had a pad hull, bass boat. My current boat is a 2002 1750 Crestliner Fish Hawk and after buying a TP Hustler ported, found that I too did best, with this boat and it's intended use, after plugging them. Reason being, I wasn't interested in hole shots and WOT MPH and I had to run this new one to realize that. I am more interested in mid rpms, cruising if you will, with this boat and the holes for that are a nuisance. But I am enjoying the rake and cupping assets doing what they were designed to do........and Crestliner's reverse chines.....really an asset for fast planing and a dry ride.

Totally agree

my less used boat, the Campion Chase is a fairly quick thing at a couple mph off 70 gps...and has a pad. But not in the same league As bass boats in general. I never found the need for any size of hole in the pvs and plain just didn’t like the feeling of it. I mainly spent my time cruising in that and occasionally opening her up when conditions allowed it. Which isn’t often here in Scotland.
Being honest though...it wasn’t by any means ever quick out the hole. Even with the smaller pitch 19/21” all round props like the laser 2. A good friend of mine is considered one of the best mono skiers around here. Even he said it wasn’t ideal to get up with. I tried it and it was near on impossible for me. She isn’t generally used for treat though...so no big deal.

 

[QBhoy]

drink more beer...... you get less fussy

Oh you are right Scott. I wish I could. I just seem to have a terrible need for prop perfection. Does it exist.
I will have bored most of you guys to tears over the last few years on here. I can’t help it.
Even now with the new sensible boat...I’m still hunting the dream prop. Very close to it with the 19” enertia....but hell...I can’t help but think what a 20” might be like. And so it goes on !!