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Bad Porpoise

Old 01-23-2008, 10:46 AM
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Originally Posted by hotlavey
I have a Lavey 2750 that had a bad porpoise problem over 70 mph. After I put a Whipple on it it really got exciting. I tried different props, 4 & 5 and no help. Finally had the bottom blueprinted and removed a couple lifting strakes and went with a 2" Imco shortie with a Hering 5 blade. Now I can run low 90's with no bounce at all, almost can run it hands off, and no tabs. Very happy but a little poorer.


Sounds fun....and sounds like a bravo eater with that whipple and 5 blade.
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Old 01-23-2008, 03:28 PM
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Originally Posted by tblrklakemo
Sounds fun....and sounds like a bravo eater with that whipple and 5 blade.
It is quite an improvement for sure- I fought it for 5 years and went back and forth with Lavey, who were no help at all- said it was driver, not the boat. Turns out it was the boat. Now it's fun, and we have gone by a few Bravo's, but there are sure alot more that will go by us. At least we're not bouncing when they do.
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Old 01-23-2008, 07:08 PM
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My 270 hallett only porpoises in flat to semi flat water. Before the engine upgrade it would porpoise around 68 to top speed of 75mph. I purchased a 5 blade Maximus and it helped a little but still porpoised in flat water (The five blade did carry the bow a little higher at higher speeds).

Talked to Hallet and received no useful info.

Since the upgraded HP (800hp and -2 IMCO drive) the boat still porpoises around 70 to 80 in flat water and goes away up to about 90mph. I currently have a stock 4 blade 32p prop with the engine upgrade and won't put on a 5 blade since the outdrive (XR) won't last with that much HP and bite from the prop.

I personally think the Hallet 270 is a heavy boat for it's size and to try and maintain the bow up at the higher speeds in smooth water is asking a lot from the prop (bow lift). I guess that is why the Hallet rides so smoooooooth in rough water. Take the good with the bad. I've have to admit the boat handles like a dream above 80 and besides the inconveince of the propoising in flat water it's very stable.... I do notice that the porpoising reduces with less trim which is expected since the prop is not trying to lift the bow as high.
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Old 01-23-2008, 09:08 PM
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Before I spent a ton of time and money on anything else try a little smaller diameter prop.
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Old 01-25-2008, 11:09 AM
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Originally Posted by VegasHallett
My 270 hallett only porpoises in flat to semi flat water. Before the engine upgrade it would porpoise around 68 to top speed of 75mph. I purchased a 5 blade Maximus and it helped a little but still porpoised in flat water (The five blade did carry the bow a little higher at higher speeds).

Talked to Hallet and received no useful info.

Since the upgraded HP (800hp and -2 IMCO drive) the boat still porpoises around 70 to 80 in flat water and goes away up to about 90mph. I currently have a stock 4 blade 32p prop with the engine upgrade and won't put on a 5 blade since the outdrive (XR) won't last with that much HP and bite from the prop.

I personally think the Hallet 270 is a heavy boat for it's size and to try and maintain the bow up at the higher speeds in smooth water is asking a lot from the prop (bow lift). I guess that is why the Hallet rides so smoooooooth in rough water. Take the good with the bad. I've have to admit the boat handles like a dream above 80 and besides the inconveince of the propoising in flat water it's very stable.... I do notice that the porpoising reduces with less trim which is expected since the prop is not trying to lift the bow as high.
Hmmm...a five blade ? what pitch ? do you still have it ? what rpm did you turn it ? mph ?
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Old 01-25-2008, 04:20 PM
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Originally Posted by HALLETT FAN
Hmmm...a five blade ? what pitch ? do you still have it ? what rpm did you turn it ? mph ?
I sold the five blade, I had a 4 blade 28 and purchased a five blade 26 before the big HP upgrade. They both turned about 5200 and the top spped was within 1 mph of each other (74 to 75). I noticed a better cruisng rpm with the five blade (minus 200 rpm's vs the four blade). However it really did not help much with the porpoise issue.

The 5 blase was labbed by Mercruiser which had the diameter turned down to about 15 1/4" from the stock diameter. My prop slip went down but I think the my XR gears paid a price for the five blade prop. I took the new drive apart to install the -2 lower unit and noticed some wear issues on the gears. I only had a couple of hours on the drive and most of them was with the five blade. I was always easy coming out of the hole and changed my drive oil every 10 hrs. The marine shop (GT marine) even gussed that I was running a five blade from looking at the gears when they were taking it apart. I never told them I had a five blade and the prop was already sold.

Hope this info helps....
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Old 01-28-2008, 06:38 PM
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Originally Posted by hotlavey
It is quite an improvement for sure- I fought it for 5 years and went back and forth with Lavey, who were no help at all- said it was driver, not the boat. Turns out it was the boat. Now it's fun, and we have gone by a few Bravo's, but there are sure alot more that will go by us. At least we're not bouncing when they do.
zz

Last edited by hotlavey; 01-28-2008 at 06:40 PM. Reason: delete
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Old 01-28-2008, 06:40 PM
  #18  
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Originally Posted by tblrklakemo
Sounds fun....and sounds like a bravo eater with that whipple and 5 blade.
That's what I've heard, but my XZ drive seems to be holding up so far.
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Old 01-28-2008, 08:39 PM
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Hallett Fan: I have a new unlabbed 30 pitch Maximus. Ran it once for testing, but like VegasHallett I have been reluctant to put the wear on the XR gears.

Hot Lavey: Where did you get your bottom blueprinting done? I've considered this.

Last edited by zahndok; 01-28-2008 at 08:42 PM.
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Old 01-29-2008, 09:50 AM
  #20  
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Gears wear. Shavings are normal. Chunks are not. Most wear occurs in the first few hours of usage.

5 blade propellers will not wreck a drive if used in the proper methods and with the proper HP ranges per the drives capabilities.
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