Boat porn of a 25 Seafari beasty

bigfluke · #1 10-14-2007, 11:40 PM

My company has used a 25' Seafari for very deep-v planing hull and propulsion research for the past 4 years. The discussion in this thread has been helpful to understand the boats general performance. When I bought the boat in Florida the engines and drives were shot so I never ran the boat in its original configuration. The discussion about Moesley's plan to have an integral ballast system in this boat makes a lot of sense based on our findings that the boat was more seakindly and we could eliminate the chine walking, heeling and porpoising by a more forward lcg and other tricks. In fact our testing at 4800 lbs, through 7400 lbs was done by installing ballast to achieve a 0 degree static trim which equates to a 37% lcg.

Bigshrimpin · #2 10-15-2007, 02:45 AM

BigFluke - Welcome! what kind of speed did you see from the hull before it started to chine walk and what type of ballast did you use? were you testing other hulls or just the 25 seafari?

strick · #3 10-15-2007, 03:21 AM

Bigfluke- Ditto's on the welcome. However I was a little disappointed I did not see the 25 seafari in any of the boat pictures on your company's web site

http://www.navatekltd.com/index.html

Chuck and Scott thanks for clarifying.

strick

Bigshrimpin · #4 10-15-2007, 03:35 AM

This thread keeps getting better and better!!!

Yikes! Steven - I didn't realize who I was talking too . . . and I understand if this information is proprietary. I was just curious.

Forgive me here . . . but isn't 37% LCG way far forward for a powerboat?

bigfluke · #5 10-15-2007, 07:47 PM

We tested the Seafari at weights from 4200 to 7400 lbs and with lcg's from 27% to 37% so handling isssues happened under many different circumstances. Our first tests were to develop a novel drivetrain with a 480 hp Yanmar and Weismann surface drive and we achieved 45+ knots @ 7400lbs. Current test configuration is with 300 hp Yamaha outboard on a Porta bracket. Our focus has been to move lcg as far forward as possible to improve pitch behavior without compromising following sea handling. Our hydrodynamic tricks to the hull bottom have been focused at reducing the increased drag which comes with a forward lcg. We have already yielded a 3+ knot improvement in speed and expect to see +5 knots on the next experiment. The info that Moesly had intended a ballast system makes a lot of sense from what we've experienced in running the boat with lower and further forward lcg. The basic boat has outstanding seakindliness at all headings when weight and lcg are dialed in. When we finish all of our research we expect to see a 15% improvement in speed/power and elimination of the handling problems that are inherent in many narow, deep-v hulls with fine entry. I consider Moesly along with Hunt, Hickman and Lorne Campbell to be creative innovators who have made major contributions to planing hull technology while achieving balanced and producible designs. I am delighted to have learned that Moesly planned an integrated ballast system which would have eliminated the sub-par performance issues with the Seafari. I'm sure if he had continued the development of this boat it would have truly been an outstanding performer and benchmark for its size.

NoBones · #6 10-15-2007, 08:55 PM

Quote:

Current test configuration is with 300 hp Yamaha outboard on a Porta bracket.

Scott Porta's shop is in Edgewater FL. close to Everglades Boat and Boston Whaler.
He has a heck of a shop and does nice work. Scott has always
been innovative in the marine industry.
You would be surprised at the amount of boat manufactures
in Florida alone, currently there are 556.
Alot goes on here that few even realize.
I love being a Florida Cracker.....

See ya, Ken

glow · #7 10-19-2007, 10:17 PM

Excuse me for my ignorance. What is lcg, lower center of gravity? Thanks, Greg

Bigshrimpin · #8 10-20-2007, 02:17 AM

Longitudinal Center of Gravity. The lower the percetage . . . the further forward the point is towards the bow.

mbo_1971 · #9 10-20-2007, 09:55 AM

what is an average for us non technical types? 37% is an interesting number, but is it 37 vs 75 or 37 vs 45? Thanks.....

Bigshrimpin · #10 10-20-2007, 05:21 PM

I'm no boat designer, but I've read that most Deep V hulls have LCG well past mid ship like 60% + , but I don't really know.

I can't remember if there was a difference b/w lcg and LCG? I think they have different meanings. Where's the BigFluke when you need him