Capt John wrote:
On Jun 13, 3:18 pm, HK wrote:
trainfan1 wrote:
HK wrote:
I know someone considering the purchase of a 21' Parker center
console, the model with the 21-degree transom deadrise. The boat
itself weighs 2750 pounds. Great open fishing boat.
Parker recommends three Yamaha engines in its four stroke line: 150
hp, 200 hp and 225 hp.
For a boat with the same hull but with a pilothouse cabin that brings
the hull weight to 3250 pounds, the Yamaha performance page indicates
a top speed of 39.3 mph with the 150 hp engine running 5600 rpm and
burning 17.5 gph. At a cruise speed of 25.6 mph at 4000 rpm, the rig
burns 7.8 gph.
I'm recommending the 150 hp engine for the 21-foot center console. I'm
guessing a top end of 42-43 mph with a fuel burn of 15-16 gph, and a
4000 rpm cruise of of 27-28 mph, burning 6.5 to 7 gph.
I don't see any need to step up to a 200 hp V6 on this boat. The days
you can comfortably run more than 25 mph in a 21' boat are rare on
Chesapeake Bay. The 150 is about $4000 less than the 200.
Any comment on the extrapolations?
You're still going to have the engine running at 5600 rpm WOT, and
burning 17.5 gph, with a different prop, maybe.
I'm surprised the cruise engine speed is as high as 4000 rpm, but this
is a 4 stroke. It's also quite a bit of fuel at WOT for any stock 150.
No E-Tec options to consider?
I know... it's a Parker.
Rob
I doubt the engine will be running at 5600 rpm. No one I know wants that
kind of fuel burn.

We got a data sheet faxed from Parker. Their sheets are pretty reliable.

4000 rpm happens to be the sweet spot for these four stroke Yamahas. It
is on my 225, too.

The data sheet says 16 gph at 5600 producing 40.9 mph, and 7.30 gph at
4000 rpm producing 26.2 mph. That's pretty close to my guess
extrapolations. No reason to go to a 200 or 225 hp.

Naw. Not interested in an Evinrude eTec. I like four stroke engines.
So does my friend.- Hide quoted text -

- Show quoted text -

I wouldn't be so quick to toss the idea of a two stroke.

They weigh less, which is always a good thing on a small boat. Their
far less complicated, which helps for long term reliability and cost
of repairs/ownership. The fuel injected 2 stroke engines burn less
fuel. They cost less to buy, and you run them at lower RPM's than a 4
stroke to get the same power, so the 4 stroke is probably going to
wear faster. OK, you do have to add oil to a 2 stroke, but you have to
check the oil, change it and change oil filters on a four stroke. Is
the yard going to let you do that? So you've probably got to pay for
that, and we all know how inexpensive yard bills are. Two strokes have
been around for a long time, you know their reliable (I'd get a Merc
over the Yamaha any day),

Nothing really wrong with Yamaha except for where they're built & where
the $$ end up...

4 strokes are still new,

?

http://hometown.aol.com/homelite55/

Old technology, to some.


and new products
have their problems. I wouldn't even consider a 4 stroke, especially
on a small boat. My two cents.

They have their place at times, but the 2 strokes are getting so good so
fast now.

Rob



John