Engine HP Formula

[stevebirch2002]

Hi All

The formula that I have used is a standard one and I have copied it from the
book "How to install a new Diesel" by Peter Cumberlidge ISBN 0-7136-3777-3

Page 3

S DIVIDED BY SQUARE ROOT OF WL= 10.665 DIVIDED BY THE CUBE ROOT OF (D DIVIDED
BY SHP)

S / vWL = 10.665 / 3v(7000 / SHP)S = SPEED (6.25 NEAR TO THEORETICAL MAX OF 6.75)
WL = WATERLINE LENGTH IN FEET
D = DISPLACEMENT IN POUNDS (7000 FOR A LOADED VEGA)
SHP = SHAFT HORSE POWER REQUIRED

With transpostion of formula the SHP calculates out at 12.77 HP but with the
extra 5% needed for bearing, sterngland friction etc it calculates to 13.41HP

Just my two penneth worth.....

Kind Regards to all

Steve Birch Vega "SOuthern Comfort" V1703

 

[bbach1949]

Steve: Interesting formula. In an earlier post, you said you thought the
Yanmar 2GM was too much power for a Vega. My 1984 2GMF is rated at 13 hp
(continuous) and 15 hp max. I know that the new 2 cylinder Yanmars make 15+
horsepower continuous and are rated at 18 hp max. Now those might be too
much, but mine seems just about right. I know you are selling Beta, and I
agree that yours is a good fit for a new conversion, but we shouldn't steer
people away from older 2 cylinder Yanmars. Just my humble opinion. Bill
Bach, V1071

 

[stevebirch2002]

Hi Bill

I agree totally and I am trying to keep away from the fact that I sell the
Beta
engines to Vega owners. The older Yanmars were rated at 15HP but were a bit of
a tight squeeze. The same way as a few Vega owners have bought the Beta BD722
from me that is rated at 20Hp whixh I belive is too big. All I am trying to
say
is the ideal HP for a Vega is between 13 - 15 HP, what engine it is doesent
really matter as long as it has:

1. Diesel
2. Available spares at a fair price worldwide
3. Indirect cooling if you intend to sail in salt water
4. Ease of access to maintenace points
5. Ease of installation
6. Price has to be competitive!

I know this points slightly to the Beta and so it should as I took over two
years visiting all the engine people in the UK and finding out what points
above could be catered for. In the end it came down to the Beta and the Nanni
which are both based on the Kubota. I chose the Beta as the company changed
the
feet mountings to fit direct into the diesel Vega, took care and time to
explain everything, gave a reasonable discount and more importantly seemed to
care about their customers. The press in the UK always seems to praise Beta
for
their customer relationship. The only time we had aq problem, Beta sent a new
engione and engineer to install it. It actually proved to be a previous
installation fault but there was still no charge from Beta.

Kind Regards to all

Steve Birch (talking as a VEga owner, not Beta supplier!)

At 23:10 16/01/03 -0500, you wrote:

 

[wxt8981]

About the Yanmar 1GM
I installed this engine May 1996 by myself- it took some grinding and
adjustments,
but besides a lot of dust it wasn't that difficult.
Since then, besides regular maintenance, I had to replace the impeller.
No big deal;
I carry 2 extra impellers with me, and of course filters and belts-
just in case.
I love that engine- no fuel-smell (which was not the case with the
Albin 0-21),
it runs and runs (a bit noisy, but maybe some day I install some
insulation) and it
uses little fuel. The only thing I dislike is the 3-blade prop- I don't
let the prop free-
wheel when sailing and that creates a lot of drag.
I feel comfortable with that little engine- and think that's important.
Wilhelm V-257

 

[bbach1949]

Steve: I agree that the Yanmar 2GM is a tight fit in a Vega. It's not easy to access the fuel pump, especially. Otherwise, it meets all your criteria, and has a good reliability record. I think if I were repowering today, however, I would go with the Beta or other that were smaller and lighter. Luckily I don't need to repower! By the way, I absolutely love the tiller and coaming seats I got from you and would recommend them to all. Bill Bach V1071