21 or 20p 4 blade

[HVAC Cruiser]

Re: 21 or 20p 4 blade

Thats really is a WAG....But you have a cam that should not run out of steam at the top and if it does...well eldobrock performer will fix that..Personally i would stay with a 4 blade, your pushing 4000 plus lbs you need blade area and lift that hull looks like a deep v so lift will only aid in planing...

I watched the video and your bow is up and it looks like your just getting on plane....Is that the break point..thats not 39mph or 4000 i hope..If it is you have spun hubs...aka your climbing ontop of the pressure wave and the prop lets loose

Pic 1 your climbing out...is it slipping at all..Is that full throttle??
Pic 2 your on plane...Is the prop now slipping if you gun it a bit?


1.Can you slam the throtte and power to plane with no slip
2.Do you have to ease it to plane or she starts slipping

I am wondering here if your not being kind to your new motor and gently applying power getting you around...masking a spun hub or some issue...You should be able to nail it from and it should respond sharply with that much tourqe say for 20 to 40 no slip what so ever...Then this would all make sense that is it blows at 40 even gently nudging it past that speed creates cav

What would happen if you just pinned the throttle form 0 to 35 would it slip or cavitate????

I can power up to plane without any slip
with pic 2 from the point its at if I gun it ( I haven't really nailed it just tried to slide up to it so to speak), it hits about 4k and blows out and I have to back down not to break anything it almost feels and sounds like I missed a gear shifting, revs go up boat slows down and its get off the throttle before I blow something up. another way to describe it is over centering a clutch when power shifting a car & it can't take the torque & centrifugal force

I just watched my videos again. The 1st one was just coming out of the channel and easing up to 20-25. my wife took the pic of me driving at the time, its the one in my avatar I wasn't even 1/2 throttle. the 2nd one I was doing about 28 just cruising.

The engine and the drive are still fresh with only 7hrs now on them I climb up nice and slow I have never tried to just jump on it. I am going to try to get out on sunday by myself in the morning, I will do some more tests and give it a shot. I don't want to give my kids heart failure lol.
As it is now even with the problems I am having, when I go from idle to 2k fast it will pin you to your seat, last time I did that my son called me a maniac lol, its not that your going fast, just feels like it is hehehe.

I am going to order the new prop I will get the 23 4 blade you linked to ??.
Right now I have the old iron manifold on her I do have a torquer manifold, high flow open plenum I will toss on to get some more power out of her if needed.

According to the comp cams software with the std manifold I am doing 440 ftlbs torque at 2000 rpm & 312hp@ 4000,...... Hum, I wonder there is that magic # again 4k . Switching to the torquer manifold Not the torquer II, I have the old style , would slide the curve to 443 ftlbs @ 3500 & 338hp @ 4500

Another thing I think I am going to do is go to a public scale and weigh the trailer and boat, get a transient slip for a day and go back and weigh just the trailer to get a true weight on the boat.

 

[Tail_Gunner]

Re: 21 or 20p 4 blade

I can power up to plane without any slip
with pic 2 from the point its at if I gun it ( I haven't really nailed it just tried to slide up to it so to speak), it hits about 4k and blows out and I have to back down not to break anything it almost feels and sounds like I missed a gear shifting, revs go up boat slows down and its get off the throttle before I blow something up. another way to describe it is over centering a clutch when power shifting a car & it can't take the torque & centrifugal force

I just watched my videos again. The 1st one was just coming out of the channel and easing up to 20-25. my wife took the pic of me driving at the time, its the one in my avatar I wasn't even 1/2 throttle. the 2nd one I was doing about 28 just cruising.

The engine and the drive are still fresh with only 7hrs now on them I climb up nice and slow I have never tried to just jump on it. I am going to try to get out on sunday by myself in the morning, I will do some more tests and give it a shot. I don't want to give my kids heart failure lol.
As it is now even with the problems I am having, when I go from idle to 2k fast it will pin you to your seat, last time I did that my son called me a maniac lol, its not that your going fast, just feels like it is hehehe.

I am going to order the new prop I will get the 23 4 blade you linked to ??.
Right now I have the old iron manifold on her I do have a torquer manifold, high flow open plenum I will toss on to get some more power out of her if needed.

According to the comp cams software with the std manifold I am doing 440 ftlbs torque at 2000 rpm & 312hp@ 4000,...... Hum, I wonder there is that magic # again 4k . Switching to the torquer manifold Not the torquer II, I have the old style , would slide the curve to 443 ftlbs @ 3500 & 338hp @ 4500

Another thing I think I am going to do is go to a public scale and weigh the trailer and boat, get a transient slip for a day and go back and weigh just the trailer to get a true weight on the boat.

Get the 23 and pin it from o to 35 and listen close for slip...keep the leg in all the way make that hub work hard . You have to isolate the issue....hub...speed...or rpm....New prop and 3 bad hub's....notta chance hard acceraltion will stress the power train...Speed will stress the hull or hull drag and components..Take the tabs out of the loop and them put them back in.....You wouldnt have a hull thats badly hooked....aka rotted stringers...and a buckling hull at speed...Just reachin there

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

Get the 23 and pin it from o to 35 and listen close for slip...keep the leg in all the way make that hub work hard . You have to isolate the issue....hub...speed...or rpm....New prop and 3 bad hub's....notta chance hard acceraltion will stress the power train...Speed will stress the hull or hull drag and components..Take the tabs out of the loop and them put them back in.....You wouldnt have a hull thats badly hooked....aka rotted stringers...and a buckling hull at speed...Just reachin there

Got It

I won't have the new prop by the weekend BUT I am going to take her out alone & will put her to the test, an early morning run I want to do it in relatively calm water, just looked at the sea report looks like it is going to have to be Monday morning http://weather.noaa.gov/cgi-bin/fmtbltn.pl?file=forecasts/marine/coastal/an/anz335.txt

The hull isn't hooked, and I core drilled the stringers and transom, dry as a bone + its a double wall hull, she is built like a tank lol. the only problem was the PO at some point had re-glassed the engine compartment and remounted the engine without 4200 on the bolts, they were rotted from the inside out, which I replaced with a microlam and re-glassed with 1708 biax . there are some stress cracks in the gel coat on the cap only but the boat is 26 years old
I am thinking of breaking my heart and just buying a 23p 3 blade AL prop local just to see if its the hub.
I could buy a new hub for the quicksilver 25p SS but that one was a dog off the line, at least with 4 people aboard.

I am going to see if I can mount a video cam so I can record and document the tests.

BTW, I love the trim tabs on her, I drop those puppies down it they drop the bow puts her on a flat run & puts the boat right on top makes me feel like I'm Ice skating

 

[walleyehed]

Re: 21 or 20p 4 blade

Is there anything mounted to the transom with-in 12" either side of center-line??? Can you tell if there is any chip or pocket...any damage to the hull forward of the prop???

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

Is there anything mounted to the transom with-in 12" either side of center-line??? Can you tell if there is any chip or pocket...any damage to the hull forward of the prop???

I just put a straight edge across the keel and all areas in front of the prop, the hull is flat. the bottom paint is pretty beat with chips, flaking off and all. I am going to power wash and scrape her off if Earl holds out for me and repaint tomorrow.

With anything mounted well the spedo pickup is exactly 12" to the inside, there is an old transducer at 13" to port, and a new transducer at 16" to starboard

I don't even use the spedo on he,r the pickup tube is broken. I just use the GPS I can remove it along with the old transducer if you think it might help

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

NOW I FEEL LIKE A TOTAL IDIOT!!!!!!!

I believe I found the problem with ventilating

My exhaust bellow disconnected :redface:

I can't believe I missed this, I found it tonight when I was putting my trim tabs etc back on. Since I posted the initial problem I decided to eliminate as much as possible. I stripped and sanded all the bottom paint off. I then gave her 2 coats of rusutoleum

In addition, I removed all old transducers etc not being used anymore. The new 4 blade prop is supposed to be delivered Thursday and I am doing sea trials on Friday to see if everything I have done, does the trick

My next thought is do I simply try to re-glue the bellow (its new) or do I buy and install a bellow tube instead?


EDIT- Just been reading some archives, from what I have read, tube,bellow, or nothing doesn't amount to a hill of beans

So much for me thinking my exhaust was maybe ventilating the prop. Guess I am back to square one. I just hope that between the new prop, getting the bottom as smooth as a babies bottom, and removing all the old crap off the transom. Boy this is starting to make me feel like I'm back to being a class "B", change parts till you get to the one that fixes the problem

 

[Tail_Gunner]

Re: 21 or 20p 4 blade

..........i should have known

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

..........i should have known

That I'm an idiot, or the exhaust bellow was blown off LOL

I replaced it with an exhaust tube yesterday.
Do you think the bellow could have been the problem???

 

[Tail_Gunner]

Re: 21 or 20p 4 blade

I doubt it but it could be part of the problem. Cleaning your hull will have a effect...Its just a matter of isolating where the problem is

1. clean hull..... ok
2. new prop.... ok
3. drive height.... ok
4. speedo tab...ok
5 Trim tabs
6. Hull deforming
7. coupler
8. drive

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

I doubt it but it could be part of the problem. Cleaning your hull will have a effect...Its just a matter of isolating where the problem is

1. clean hull..... ok
2. new prop.... ok
3. drive height.... ok
4. speedo tab...ok
5 Trim tabs
6. Hull deforming
7. coupler
8. drive

Ok, did some major inspecting this morning I am hoping I can rule #8 out seeing it is a brand new drive with less than 10 hrs on her. The trim tabs seem to be ok they are 23" away from the center of the drive and about 1/4" above the bottom of the boat

I ran a straight edge down the hull

she is flat as a board BUT I did notice that the last 30" up from the transom @ the chine there is a little contour although it looks like it is supposed to be there

It is at the same exact spot on both sides and it is only at the chine, the bottom of the boat & keel at that point is flat.

I checked my other Cruiser and it exactly the same in the same spot.

Guess what I have to do now is wait for the new prop to come in thursday and give it a test run. If the problem is still there it comes down to the coupler

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

So the new prop got here from iBoats yesterday But I can't go test her out because I am waiting for a hot water to be delivered to me so I can race 70mi to Montauk Point for an emergency installation.

While I wait I figured I would install the prop. my zinc was too long, so I ground it down for clearance This one is new, I really don't want to buy a new one.

Should I cut the entire tab down to above the prop or was me grinding it to give the prop 1/4" clearance enough.

I did put an edge pack on the zinc to help have a smooth flow.

Any opinions

 

[Tail_Gunner]

Re: 21 or 20p 4 blade

There is a off set tab for that problem...Dont know what to tell you but a 1/2 clearance should be safe.. If you have power steering you should not need a tab

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

I finally got to try out the new prop today I bought a14x21p instead of the 23p.
MY findings were as follows:

5000rpm=56 mph 18% slip
3900rpm=41mph 25% slip
1000rpm=8mph 43% slip

All I can say is OUCH!!!!!!

I putt putted through the harbor at 5mph then I went to 8mph because there was absolutely no one around. The slip was bad but I was fighting the current I had an 11mph head wind with 1' waves. For the open ocean tests the head wind ranged from 8.9mph to 11.2mph with .3' waves. The wind and wave data is from The Marine Buoy Forecast

I did nail the throttle a few times to try her out she was fast getting from 0 to 32 or so, a matter of seconds then to 56 was slow. As a matter of fact the rpm stayed constant at 5000, and she slowly climbed to 51 from 45 or so kind of like inertia

Could it be because its just a heavy boat?

 

[Tail_Gunner]

Re: 21 or 20p 4 blade

I finally got to try out the new prop today I bought a14x21p instead of the 23p.
MY findings were as follows:

5000rpm=56 mph 18% slip
3900rpm=41mph 25% slip
1000rpm=8mph 43% slip

All I can say is OUCH!!!!!!

I putt putted through the harbor at 5mph then I went to 8mph because there was absolutely no one around. The slip was bad but I was fighting the current I had an 11mph head wind with 1' waves. For the open ocean tests the head wind ranged from 8.9mph to 11.2mph with .3' waves. The wind and wave data is from The Marine Buoy Forecast

I did nail the throttle a few times to try her out she was fast getting from 0 to 32 or so, a matter of seconds then to 56 was slow. As a matter of fact the rpm stayed constant at 5000, and she slowly climbed to 51 from 45 or so kind of like inertia

Could it be because its just a heavy boat?

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You have come a long way from this place..

its a 22' Cuddy Cabin empty weight is listed as 3600# add the extra cabinet with the sink, stove & fridge figure + 70 gal fuel its at about 4240 before passengers.

We went out today with a full fuel tank, 2 adults + 2 kids. Our total combined weight was probably around 450# tipping the scale around 4700#

1st I used the qucksilver 25p prop, at 4000 wot I was only doing 40-42 major prop slip . Out on the water I swapped out to a beat-up Michigan Match 14 1/4 x 21 . That did better same 4000 rpm 39mph on the gps 28% slip.
The one problem I did have is it started cavitation above 4k I trimmed drive down and it really didn't help that much, I could heat the revs jump and feel the prop stop biting. I trimmed the bow up ( lifted the trim tabs) to try to get the drive deeper didn't matter.


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4400 lb cuddy doing 56mph..Not to shabby. Do you think it was the hub or the HULL...Just for giggles id drop that 25 on her and see what happens..

 

[NHGuy]

Re: 21 or 20p 4 blade

Sounds like a 4 blade 21 is key for your heavy boat. But, you are still making max rpms. Once you get the whole fam damily onboard the 21 will probably be just right. Sounds like you are getting what the stroker can give. It may be able to turn a 23 once it's run in a bit. Awesome. I'm glad for you.

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

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4400 lb cuddy doing 56mph..Not to shabby . Do you think it was the hub or the HULL...Just for giggles id drop that 25 on her and see what happens..

That I was thinking To be honest I am happy cruising at 20-25, I'm not in a race. My thing was to get her right so she got the best fuel mileage.

I am thinking it was the hub on the 25p & the prop itself on the 21p 3 blade. I noticed when I installed the new one I really had to wrench down to draw her in. The old one felt like it was sitting solid but no were close to the new one. Under 400fp it was probably slipping like a b*&h And well the 21p x3 was just pretty beat.

I might pick up a new hub for the 25p and see how she does

More important now, I found out today I have to buy a new reel for one of my poles (drag is messed up) and new line for all my reels . I lost 3 hooks today fishing for strippers when the lines broke Biggest thing I was able to get in today without snapping the line was 25".

 

[HVAC Cruiser]

Re: 21 or 20p 4 blade

Sounds like a 4 blade 21 is key for your heavy boat. But, you are still making max rpms. Once you get the whole fam damily onboard the 21 will probably be just right. Sounds like you are getting what the stroker can give. It may be able to turn a 23 once it's run in a bit. Awesome. I'm glad for you.

Hi NHGuy,

I held her at 5000, I actually don't want to run her over 4500 so a 23 or the 25 might still work. Torque - HP for the engine the way I set it up is around 4-4500 tops . I basically built the engine as a stump-puller .

Once the new drive is broken in I might swap the intake out for the torquer, and the carb for a Holley 750. When I dropped the hammer I was able to feel a little bog like she was starving