Venting the prop

[ToMorrow44]

ToMorrow, The boat is a Warlock Deckboat. It has the same bottom as there XST. The boat doesn't have trim tabs, maybe that would help. Like I said it came with a Bravo-3 and a 454 Mag motor. I put in the HP-500 and the XZ drive. The drive had a Bravo-1 28 pitch, then I went to a 26 pitch, the boat still had a hard time to get on plan. so I went to the 5- blade Hydromotive 24 pitch.
What Hydromotive prop do you have (P-5Race or P-5X)? Did it help getting on plane at all? I've heard the Hydromotives are sometimes harder to get out of the hole than a Bravo I but again it varies boat to boat. What RPM are you spinning WOT?
-Tom

[Chickenlips]

What Hydromotive prop do you have (P-5Race or P-5X)? Did it help getting on plane at all? I've heard the Hydromotives are sometimes harder to get out of the hole than a Bravo I but again it varies boat to boat. What RPM are you spinning WOT?
-Tom
It is the P-5X, not lab finish. I haven't put it on since they drilled the vent holes. When I had the prop on last year, after the boat got on plan it tached out @ 5000 w/ one person. I don't know what speed as the speedo hole was pluged, but I would guess between 65 & 70. Which brings up another question, why can't these Mercury motors get more RPM's, My motor (468 Chevy) in the V-drive would turn 6200.
If the holes work then I will do the same thing to the Bravo -1 26 pitch. Hydromotive told me that the Bravo-1 26 pitch is in there version a 25 pitch and drilling it would help, so I can use it for a spair. Thanks again for your help. Jim

[ToMorrow44]

It is the P-5X, not lab finish. I haven't put it on since they drilled the vent holes. When I had the prop on last year, after the boat got on plan it tached out @ 5000 w/ one person. I don't know what speed as the speedo hole was pluged, but I would guess between 65 & 70. Which brings up another question, why can't these Mercury motors get more RPM's, My motor (468 Chevy) in the V-drive would turn 6200.
If the holes work then I will do the same thing to the Bravo -1 26 pitch. Hydromotive told me that the Bravo-1 26 pitch is in there version a 25 pitch and drilling it would help, so I can use it for a spair. Thanks again for your help. Jim
I don't know why mercury does that. I believe the rev limiter for the hp500 is 5400? They could spin those motors faster but I guess they don't in order to make the motor live longer...? Anyway, try your vented prop and see what happens then let everyone know and I'm sure you can get it straightened out.
-Tom

[sorry dog]

R&R Prop Shop drilled PVS spec holes in my Bravo's with his CNC machine. So I can tailor the amount I need with the PVS plugs or plug it all together for the next owner.
This is the way to go. My favorite lake prop was a Merc Laser 2 because of these type of holes. My Hydrostream was sort of sensitive, but you could tell a difference in slip on takeoff between opening up only one hole a size larger. I also seem to remember that if you set it up to slip like crazy and then catch shortly afterwards then you couldn't add much weight before you had too much slip.
I also experimented with double stacking washers and using a slightly thicker washer but the slip was too much, and I didn't gain any on top.
Once on plain I never noticed the venting affecting anything.
This was on an OB setup that only partially surfaced and the mid had a few exhaust holes drilled in it.

[RiverDave]

ChickenLips, have you considered just trying a smaller diameter 4 blade? Or perhaps even a 3 Blade? If the motor is dragging ass and the prop isn't slipping, then adding more blades isn't a solution to your problem.. Dropping pitch will help the lower end but adversely effect your top end..
Find out what diameter 4 blade it was, and see if they make a smaller diameter with the same pitch that has the cruising / top end you like.. You might get lucky and the smaller diameter will slip enough to get the R's up for hole shot.. Or perhaps try going to a 3 blade as well.
Before you go modifying the drive, definately try some props with vent holes in them as well. The Drive is alot more expensive then just testing some props. Many prop shops will let you try various props until you find the one that works for you and then buy that one or one like it kinda deal.
My .02... Hope it helps.
RD

[BDMar]

ChickenLips, have you considered just trying a smaller diameter 4 blade? Or perhaps even a 3 Blade? If the motor is dragging ass and the prop isn't slipping, then adding more blades isn't a solution to your problem.. Dropping pitch will help the lower end but adversely effect your top end..
Find out what diameter 4 blade it was, and see if they make a smaller diameter with the same pitch that has the cruising / top end you like.. You might get lucky and the smaller diameter will slip enough to get the R's up for hole shot.. Or perhaps try going to a 3 blade as well.
Before you go modifying the drive, definately try some props with vent holes in them as well. The Drive is alot more expensive then just testing some props. Many prop shops will let you try various props until you find the one that works for you and then buy that one or one like it kinda deal.
My .02... Hope it helps.
RD
This is the route I would suggest...

[Chickenlips]

ChickenLips, have you considered just trying a smaller diameter 4 blade? Or perhaps even a 3 Blade? If the motor is dragging ass and the prop isn't slipping, then adding more blades isn't a solution to your problem.. Dropping pitch will help the lower end but adversely effect your top end..
Find out what diameter 4 blade it was, and see if they make a smaller diameter with the same pitch that has the cruising / top end you like.. You might get lucky and the smaller diameter will slip enough to get the R's up for hole shot.. Or perhaps try going to a 3 blade as well.
Before you go modifying the drive, definately try some props with vent holes in them as well. The Drive is alot more expensive then just testing some props. Many prop shops will let you try various props until you find the one that works for you and then buy that one or one like it kinda deal.
My .02... Hope it helps.
RD
Hi Dave, I've tryed smalle diameter,and less pitch (19pitch) but when you turn the boat it losses lift and the props blow out. The larger prop works fin after it on plan. Carter told me the boat was made to hall people not go fast, ( but I want both ) thats why he put the hole so low and used a Bravo-3. Have you found a Spectra yet( best day crusier made). Jim (Thunderbutt)

[RiverDave]

Yes I did as a matter of fact.. My g/f bought one last november and we've been running it and restoring it a little at a time. Check it out in the "How To" section under 79 Spectra 20.

[Chickenlips]

Yes I did as a matter of fact.. My g/f bought one last november and we've been running it and restoring it a little at a time. Check it out in the "How To" section under 79 Spectra 20.
Dave, I checked out the How to section. You did a perfect job on the Spectra, I'm sure your G/F will enjoy it for a lone time. When you do the interior, check out the Thunderbutt rear bench seat, where the two outside sets wrap around the motor some what, which gives the people seting in thoses seats some leg room and the person in the center also has leg room between the front buckets.

[RiverDave]

Dave, I checked out the How to section. You did a perfect job on the Spectra, I'm sure your G/F will enjoy it for a lone time. When you do the interior, check out the Thunderbutt rear bench seat, where the two outside sets wrap around the motor some what, which gives the people seting in thoses seats some leg room and the person in the center also has leg room between the front buckets.
Where can I find the pictures?
RD