major porpoising issue

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Off2sleep

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Jul 31, 2010
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Location
Bradenton, FL
I have a 23 FT DVCC that has some major porpoising issues. I.E... I was out this weekend, 12 scuba tanks + dive gear + cooler (all up in the bow), 150 gals gas and 4 guys all on board. The seas were absolute glass, motor was trimmed all the way down and I still had to use my trim tabs 3/4 down. With all that bow weight (approx 800 lbs), I was perplexed that I still had to use my trim tabs.
I might add, I always have to use my tabs when I run..., half, 3/4, full throttle, speed doesn't change it. I know my fuel efficiency is taking a huge hit.
So my question is...What should I do to change this?... Wedge mount, motor mount height, prop change? Need your help. Thanks
 
I'm having the EXACT same issue. 2008 23 DVCC. I've raised the engine - no change. Swapping to Rev 4 prop and 9x18 tabs to see if it helps. This seems to be what most are doing with this hull.
 
ryanc2":1e98qa0p said:
I'm having the EXACT same issue. 2008 23 DVCC. I've raised the engine - no change. Swapping to Rev 4 prop and 9x18 tabs to see if it helps. This seems to be what most are doing with this hull.
Click to expand...
So did you try this yourself?
 
Porposing on hulls is a phenomenon where the OB power and hull lifting strikes is trying to lift the hull up and out of the water, but the weight or 'balance' of the hull is such that it keeps dropping back down.

I have seen 4-blade premium SS props with lots of rake create stern lift, OMC Renegades is but one example.

Personally, I prefer weight towards the stern of the boat and find she'll always run faster and smoother. On the Power forums we have the tests YOU can use to check and verify 2 things - right pitch prop and right motor height.
 
Glassy seas in the Gulf off St Pete/Clearwater with a little bit of roller will make it seem as though the hull is porpoising. Believe it or not, you're essentially driving too fast for conditions as the hull is launching off the gentle glassy rollers which can be deceiving and feel somewhat like porpoising.


I don't see a 2008 DVCC all of sudden porpoising unless you have in the interim made some significant changes to the weight and balance, prop or the running surfaces of the hull ie. tabs/permatrim. I would bet the issue was the glassy seastate. Been there done that.

If you don't have them already, you can never go wrong with some 18w tabs. Better handling, better fuel economy.

Here are some Gulf conditions a few weeks ago. I had to adjust my speed to keep from lunching off those small rollers and slamming the hull on the smooth water. The sensation was similar to porpoising.

IMG_1599_zpsa6f448fa.jpg
 
In most cases proposing is the result of too little tab.
If you are still wearing the stock 12x12 tabs, consider upgrading.
 
Awesome input!
I will look at the running height of the plate. Going to check out for prop info data also. Any suggestions on the type of bigger tabs? Thanks again for your input!
 
Off2sleep":19xerbs7 said:
Awesome input!
I will look at the running height of the plate. Going to check out for prop info data also. Any suggestions on the type of bigger tabs? Thanks again for your input!
Click to expand...

Many of us with 2520's and 2530's are running 24x9 (or larger) Bennett's.
But... the 25's have a 9'6" beam so 24's might not fit the transom of a 23.
Better to wait for the 23' owners to chime in on what they have installed.
 
Ok I got some info and questions.
With 150gals of fuel, 2 people, calm seas, and trimmed up, I'm running....
WOT 43 mph @ 6100 rpms.
32 mph @ 5100 rpms
25 mph @ 4100 rpms
I can't give you the fuel consumption because that gauge stopped working today. (Of coarse) Any suggestions on where to start investigating that problem?

The motor indeed sits low as described from the past posts.
So my question is; in what order do I start to try and fix my porpoising issue?
1. Rev 4 prop 19?
2. Raise the motor height?
3. Change out factory tabs to 9 x 18?
4. Add permatrim?
5. Captain and coke double tall?

Thanks
 
Off2sleep":18zse2xj said:
Ok I got some info and questions.
With 150gals of fuel, 2 people, calm seas, and trimmed up, I'm running....
WOT 43 mph @ 6100 rpms.
32 mph @ 5100 rpms
25 mph @ 4100 rpms

The motor indeed sits low as described from the past posts.
So my question is; in what order do I start to try and fix my porpoising issue?
1. Rev 4 prop 19?
2. Raise the motor height?
3. Change out factory tabs to 9 x 18?
4. Add permatrim?
5. Captain and coke double tall?

Thanks
Click to expand...

Off2sleep":18zse2xj said:
I was out this weekend, 12 scuba tanks + dive gear + cooler (all up in the bow), 150 gals gas and 4 guys all on board.
Click to expand...

Went back and read your original post...
First off, 12 tanks and related dive gear, cooler, and 4 people is a *lot* of weight in a 23.
Even distributed well, that is a lot to ask of your boat.

Having said that, I would adjust the motor height, put on a set of 18x9 tabs, and then have that captain and coke. :D
6100 rpms sounds good to me as I believe that is a 6000 rpm motor. A touch high, but doable especially running 43 mph.

If it helps...
My 2520 MV with a single 225 OX66 runs 5100 rpm at 34 kts WOT, but it is a foot wider and almost 4 tons with fuel, people, and gear aboard.
5500 is max for that motor so I am a touch over-propped, but low and mid range performance is good, so I'm fine with that.
Not an apples to apples comparison, but I think you see what I'm getting at.
What you need to do is compare your statistics to other 23's, then go from there.
 
Megabyte":3jzvnclq said:
Having said that, I would adjust the motor height, put on a set of 18x9 tabs, and then have that captain and coke.
Click to expand...
I have lenco 12 x 12 factory tabs currently. I've looked at 9 x18s. Do I need the whole kit (actuator and all) or just the blade? And any good place to buy them?
 
If it were mine, I'd just put the 9x18s in place of the 12x12s and would be done w/ it.
 
DaleH":2oak9jm2 said:
If it were mine, I'd just put the 9x18s in place of the 12x12s and would be done w/ it.
Click to expand...
All I need is the replacement blades correct? I found them at west marine for $284 for the pair. Dale, I'll have the captain and coke for you!! :lol:
 
You probably have 12x12 edge mount tabs, at least mine are. The 9x18 tabs offered by Lenco are their standard line and carry a minimum of 14" transom height vs 11" on the edge mount. They recommended going with 12x18 edge mount replacements because of this.
 
Don't have much porpoise issue, must be weight issue as I travel light and have found in any load it is a balance of speed, sea conditions and tabs.What prop do you have now if i missed in the post ?
 
off2sleep,

I had a 2300DVCC 2006 model year with a 250 HP Yami, what I did was motor second hole from the top, Rev 4 19 prop, changed the OEM Tabs which were 12x12 edge mount with 12x18 edge mount, just changed the blades and kept same actuators in same position, had to fill/drill some holes, this set up made a world of differance, you can check with Ryan C as I sold my boat to a friend of his and he can let you know how boat handles and rides, the trick is bigger tabs.

Robert
 
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