Sailors Powerboat

Sail4beer

Usual suspect
10,035
3,421
Toms River,NJ
Is that what this is?

8AE95C1E-EC5B-4EE7-A516-CEDFEF5D9738.jpeg

 

socalrider

Super Anarchist
1,390
749
San Diego CA
Well with a beam of 10’ she might need it!
The article I linked mentioned the owner having a mooring at Howland's landing, which is just S of Emerald Bay.  That pic could be of that mooring.  Like a lot of Cat mooring fields it can get really rolly (bow & stern, waves don't always line up with wind anyway).  I suspect a narrow beam ULDB powerboat would be pretty lively, so not surprising if they used some version of a flop stopper.  We have two!

 
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ProaSailor

dreaming my life away...
6,106
794
Oregon
That looks like the perfect Catalina boat. 

Google turned up this article on her: https://www.powerandmotoryacht.com/blogs/still-cruising-after-all-these-years

25kt, 4-5nmpg.  Amazing if true.
Great article about SARRISA.  But yeah, the mileage claim is "Amazing if true", considering "he still runs the boat at full throttle wherever he goes".

What developed was a 48-foot by 10-foot-10-inch ultra-light displacement boat (ULDB), weighing 12,000 pounds dry. Powered by twin 158-hp Volvo diesels with propeller pockets, Sarissa would run 25 knots.
How is it possible for SARRISA, weighing perhaps 7 tons loaded (vs. 1.8 tons) with 12+ times the horsepower (316 vs. 25) and running more than twice as fast as Wilhelmina (25 knots vs. 11 knots) to get "around 4 to 5 nautical miles per gallon" compared to Wilhelmina's 9.6 NM per gallon?

 

nige

Super Anarchist
Great article about SARRISA.  But yeah, the mileage claim is "Amazing if true", considering "he still runs the boat at full throttle wherever he goes".

How is it possible for SARRISA, weighing perhaps 7 tons loaded (vs. 1.8 tons) with 12+ times the horsepower (316 vs. 25) and running more than twice as fast as Wilhelmina (25 knots vs. 11 knots) to get "around 4 to 5 nautical miles per gallon" compared to Wilhelmina's 9.6 NM per gallon?
Yeah, I struggle to believe those numbers.   Obviously it will be relatively efficient with that length/beam/weight but it can’t be that efficient at that speed.

the article also says the boat goes 25th and that the owners runs it at full throttle everywhere, those engines at full throttle must be drinking diesel faster than that.

very skeptical, but cool if I’m wrong ;)

 

fastyacht

Super Anarchist
12,928
2,596
It is not complocated.

If she runs 25k wrt and she has 306hp. Then she drinks 16 g/hr. Thay is 25/16 nmpg.

Lets do it another way too. Give her credit for uldb and from Crouch say 70lb/bhp at 30 MPH. 14k/70 = 200 bhp. That would be 10 g/h.

So between 1.5 and 2.5 nmpg at 25 to 26 kts range

 
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kimbottles

Super Anarchist
8,055
783
PNW
It is not complocated.

If she runs 25k wrt and she has 306hp. Then she drinks 16 g/hr. Thay is 25/16 nmpg.

Lets do it another way too. Give her credit for uldb and from Crouch say 70lb/bhp at 30 MPH. 14k/70 = 200 bhp. That would be 10 g/h.

So between 1.5 and 2.5 nmpg at 25 to 26 kts range
For an interesting comparison let’s check the Tim Kernan further development of SARRISA.

My WHITECAP (ex DRUMBEAT) was designed by Tim as an updated SARRISA and Michael Peters was involved (Peters later actually owned her.) I lent WHITECAP to our son Brent last year and sent him off with a full tank of diesel. After he returned the boat (he offered to refill the tank, but I refused to let him) I refilled the tank and found that at his reported cruising speed of 16-18 knots (3000 rpm) he burned a total of 9.76 GPH with the twin Yanmar 6LPA 201 hp continuous rated diesels. WHITECAP weighs 22,200 pounds and is 48’x12’. So there is a point on the curve that you guys can ponder. (WHITECAP’s full throttle speed is 25 knots, but we never run her there, too noisy.)

BTW, I have been aboard SARRISA and can report she is a very cool vessel. Simple but very cool. If I didn’t already have WHITECAP I would be very interested in acquiring SARRISA.

(I purchased WHITECAP from the son of SARRISA’s original owner. I believe his sister is the current owner of SARRISA. Small world.)

 

fastyacht

Super Anarchist
12,928
2,596
Whitecap at 17k is running in the transition range but those are good numbers for that speed regime. The Peters SARISSA at 25kt is fully planing. Sarissa has a Dis/(.01L)^3 of 100. Whiecap has 155 which is still quite light by modern standards. I assumed 40 dwl in both cases

 
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kimbottles

Super Anarchist
8,055
783
PNW
Whitecap at 17k is running in the transition range but those are good numbers for that speed regime. The Peters SARISSA at 25kt is fully planing. Sarissa has a Dis/(.01L)^3 of 100. Whiecap has 155 which is still quite light by modern standards. I assumed 40 dwl in both cases
I think WHITECAP LWL is closer to 44’ her hull is 48’ LOA. 

1.74 nautical mile per gallon is real per my data (I keep a log.)

0CF00A4C-BF5D-434C-8339-A0F53F506F83.jpeg

 

kimbottles

Super Anarchist
8,055
783
PNW
Whitecap at 17k is running in the transition range but those are good numbers for that speed regime. The Peters SARISSA at 25kt is fully planing. Sarissa has a Dis/(.01L)^3 of 100. Whiecap has 155 which is still quite light by modern standards. I assumed 40 dwl in both cases
WHITECAP comes up on plane around 14-15 knots, you can really see the reduction in her wake when she makes it up. She does not have much bow raise when she makes the transition. I run her at 16-18 knots because Paul Bieker and Eric Jolly told me that was the most efficient speed for her kind of vessel. I run my 2000# skiff at that same speed. Narrow boats are best in my world.

 
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fastyacht

Super Anarchist
12,928
2,596
(Transition, semiplaning etc are slippery rather ill defined terms. At 17k she should be running transom dry but not likely chines dry. Fully planing in n.a. technical terms is full dynamic lift or chines dry or with cg vertically back up to zero speed position. Or some part of these. A froude number somewhere above 0.8 or so is in the range where all of these tend to be complete...all vary with hullform.  In terms of the curve of horsepowe, in transition we see something other than a near constant exponent of a touch less than 3 which takes over above that speed.)

 
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ProaSailor

dreaming my life away...
6,106
794
Oregon
I run her at 16-18 knots because Paul Bieker and Eric Jolly told me that was the most efficient speed for her kind of vessel.
If you had one of these gadgets mentioned by @kokopelli you would know the most efficient speed in real time, perhaps taking conditions into account?

View attachment 499974

These may be narrow compared to typical power boats of similar length but they are still "fat" compared to performance multihulls, which may have LB ratios three or four times higher (skinnier).

  • Wilhelmina LB: 3.7
  • SARRISA LB: 4.0
  • WHITECAP LB: 3.7

NMPG seems like a good measure of efficiency, I wonder which boat in this thread wins the prize on that basis?  A quick review of the first few pages shows some interesting contenders, though it's not always clear whether the claims are mpg or nmpg.  To be fair, some acknowledgment must be made for accommodation/payload capacity, since small skinny boats can do very well in optimal conditions.

 

nige

Super Anarchist
NMPG seems like a good measure of efficiency, I wonder which boat in this thread wins the prize on that basis?  A quick review of the first few pages shows some interesting contenders, though it's not always clear whether the claims are mpg or nmpg.  To be fair, some acknowledgment must be made for accommodation/payload capacity, since small skinny boats can do very well in optimal conditions.
 Its NMPG at what speed that is really the relevant question depending on your goals ; )    And there are VERY different boats being compared in this thread.    A fully foiling boat or a PT (lightweight) skiff would win there, but then there are limits on what you can do with it ; ) 

I love the NMEA output from the engines though and have the same (smaller) display, its why I chose the Honda 40's on Totoro, they were the only MFR that gave the NMEA data on that size engine.     

 
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ProaSailor

dreaming my life away...
6,106
794
Oregon
I would think this boat would be pretty efficient…..wish I had more information about her.

View attachment 501232
Feather, located at Bagnall Boat Builders, Milford, Auckland, New Zealand

https://goo.gl/maps/w353VwPQiDVpx5Uc8

Source: https://waitematawoodys.com/2015/07/10/feather/

"Tony Barker on August 5, 2015 at 11:22 am said:
My brother David built and owns Feather. He now lives in Devonport, hence her move from Doves Bay to Milford. David has done a few trips up and down the coast. He usually cruises at about 8 knots, which is in keeping with the design, but can reach high speeds if the need for a quick passage arises. He has a similar lightweight outboard powered boat at his other home on an island out from Vancouver."

Contact? https://www.davidbarkerartist.com/

Larger photos:  (~3.5 MBytes each)

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P.S.



One more, same thread:



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