if theres nothing to move in the boat to correct the cg, and it is way to far back, what is the next best option??? leave it or ad weight in the bow???

Bow tank,but you pay the price as every gram takes power to move it.

Good thing about a tank is you can fill it when you need it and empty it when you dont, where just adding weight will hurt a bunch when you don't need it. the farther forward you put it the less amount you need.

80+ with 225 promax and 28 choppers.. I like the lighter weight of the 2.5's on the boat

https://lh4.googleusercontent.com/_m..._4143432_n.jpg
https://lh5.googleusercontent.com/_m..._2332827_n.jpg
https://lh4.googleusercontent.com/_m...5_103319_n.jpg

...and a sizable bow tank adds a big polar moment of inertia which can have a negative impact on pitch stability. Shifting the large masses (engines) to achieve the desired Lcg position (with a small bow tank to fine tune) works much better from a dynamic stability perspective.

ND1

how much does shifting the motors effect a 33ft v bottom????? for instance shifting motors 1 inch equals how many inches of COG change???????

(weight x distance)/deadweight....i think. havent done any stability in a few months

What's that formula giving you???

the moment. shows how far it moves. if you also must raise the motor a little, that messes with VGC ( vertical center of gravity). use the same formula

Steve
Do you know how much a 33 newer style with twin big blocks weight with fuel?
Thanks

deadweight would be hull without the power correct???

and is it distance moved or distance from COG

It’s essentially a simple summed Mass X Distance calculation. For round numbers, if:

1) The boat AU weight was say 8,000 pounds;
2) The combined weight of your engines (only) was say 2000lbs;


then movement of your engines 1 inch forward would move the lcg about a quarter of an inch. If you moved them a foot forward your lcg would move about 3 inches forward.

However if:

1) Your current Lcg was say 11 feet from the transom;

and

2) The combined engine center of mass was 5 feet from the transom;

-then 100lbs of additional ballast 30 feet from the transom would have roughly the same effect as moving your engines a foot forward. However as Steve mentioned that’s 100 lbs you don’t need to be carrying around and of course from a dynamic stability perspective this extra mass is also generating a moment of inertia of roughly 35,000 ft/lbs. The large mass of the engines is generating a moment of inertia of only 72,000 ft/lbs due to their proximity to the overall craft lcg so you can see how only 100lbs of ballast right at the bow can generate almost half the moment of inertia of 2000 lbs worth of engines somewhat proximate to the lcg. That’s why you want to keep the bow light and shift your engines to optimize lcg position. This is yet another reason why you see rough water V-hulled race boats with staggered engines-provided of course they have steps…but that’s another conversation for another day…

ND1

i got ya.....

http://en.wikipedia.org/wiki/Metacentric_height
there ya go

Sixmassive -you’re barking up the wrong tree here. Metacentres are generally utilized for stability calcs in the lateral domain (roll stability). 302sports’ issue is not in this “transverse” domain but rather the longitudinal domain –where vcg’s are not the dominant variable or concern.

ND1

NDI

Can you elaborate on why the v's would have to have steps?

][/QUOTE]This is yet another reason why you see rough water V-hulled race boats with staggered engines-provided of course they have steps…[QUOTE


Thanks, great info on CG -- the term is thrown around all the time -- now it means a litlle more...

i was just giving him something to go on. i know the differnce between longitudinal and transverse stability as i deal with it everyday. Although i havent had to long hand it in a while.
I guess thats what i get for not reading the wikipedia page haha.

This is yet another reason why you see rough water V-hulled race boats with staggered engines-provided of course they have steps…[QUOTE


Thanks, great info on CG -- the term is thrown around all the time -- now it means a litlle more...[/QUOTE]

For sure,

However as I don’t want to hijack Steve’s excellent and informative thread, I’ll start a new dedicated stepped hull thread. A huge amount of misinformation has been disseminated on this subject over the years hence this is probably the occasion to offer a new perspective. I’ll have time later this week to get this thread started -so if you could give me a few days that would be great.

Thanks,

ND1

Just spent portions of this week going through this whole thread. WOW- what greathistory on a great boat! Even saw a picture of my Dad's old 30' Shadow cat, Black Duck.

hows that run with v-rods?

surely 60+

https://lh6.googleusercontent.com/-3...0/IMG_0952.JPG
https://lh5.googleusercontent.com/-Y..._8330771_n.jpg
https://lh4.googleusercontent.com/-X..._1617361_o.jpg
https://lh5.googleusercontent.com/-O...g/s800/GDF.jpg

[YOUTUBE]http://www.youtube.com/watch?v=O2tVzvRJ11o[/YOUTUBE]

How's my 39 PP coming:party-smiley-004:

Wow what an awesome place to boat.

More Please! Steve 1, anymore lay up pictures? Thanks!

Build them with some modern technology and updated decks and dash's, and interiors....and they will come..


actually just build them the way they were..and I bet it would be successful...again..All it takes is coin..:grinser010:

I wouldn't change much. The thing that drew me to PP in the first place was that So. FL hard core offshore look.

I think boats and paint jobs in general have become too "fru fru" and could come back to some simpler designs but what do I know, probably wouldn't sell many.

+ 1.

+2

+3

+3....My Powerplay was one of the best boats I've ever owned.

Hi Wes! Still have your Apache? We're boatless, until things improve around here I'll be living vicariously through OSO to get my fix.

And yeah...those PPs are sweet, the perfect hull for LIS and the East End.

mine eats that slop right up in the sound

Hey Steve !!

Apache went to the midwest almost three years ago ! For Sale again I understand....

Now that all three kids are out of college, maybe boating is in the cards again !

Call me sometime......

+4. We LOVE ours. Personally I'd leave the "Old School" look. Although I love my big cid power......"New School" power is pretty cool.

+5. Maybe put a slightly more modern spin on the graphics for some distinction between the new and the old, but not too much.