Powercat Trawlers

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
DSe Sunshine's Aft Sections

Parmenter -

Here are two CGI images of Sunshine with her "as-designed" aft sections (ignore the size of props and rudders - the artist missed a bit on both - but the lines are a good reflection on the design). We used semi-circular sections leading aft from wave-piercing bow then tapered conically to the propeller aperture (not unlike a torpedo). At the point where we start this taper, the chine continues aft with a flat section to the trailing edge of the transoms.

Even though this image shows bottom paint on these flat sections, they were intended to be above the waterline at slower, displacement speeds - immersing into the water only at higher speeds. Initial sea trials in Zhuhai showed this to be the case as were tank tests in Shanghai. The photo of sea trials shows a bit of immersion aft at displacement speed.

We did not install enough power originally to get much beyond 9 knots - power was serial hybrid from Glacier Bay, each motor measuring maximum of 18 kW (instead of the advertised 25 kW).

We ended up installing parallel hybrid with ZF sail drive from Steyr 75 HP diesels/7 kW electric motors. We needed to reconfigure the trailing section of the bottom to accommodate these legs - not as pretty as original concept. Also, we ended up adding significant weight (diesels aft along with lots of wood and structure), so the flat sections aft were immersed along with the chine and some "ugly" sections above the chine. Top speed with these diesels remained at 9 knots.

I have also attached an "as built" photo showing the aft sections as modified for the sail drive leg. My guess is that this treatment is not unlike the aft sections of other displacement power cats - the flat sections are now well immersed (as indicated by the bottom paint). If we had more HP, I'm sure we'd break the 9 knot barrier and reach speeds in the low teens - unfortunately, our decision to use sail drive precludes more HP as they are limited.
 

Attachments

  • DSe_Sunshine_AftSections.jpg
    DSe_Sunshine_AftSections.jpg
    30.3 KB · Views: 128
  • DSe_Sunshine_CGI_Profile.jpg
    DSe_Sunshine_CGI_Profile.jpg
    76.2 KB · Views: 126
  • DSe_Sunshine_CGI_Aft34.jpg
    DSe_Sunshine_CGI_Aft34.jpg
    102.4 KB · Views: 138
  • DSe_Sunshine_SeaTrialsZhuhai.jpg
    DSe_Sunshine_SeaTrialsZhuhai.jpg
    113.3 KB · Views: 111
jtrane,
I actually kinda like it now that I've been exposed to the hulls below the WL for a few days. Looks very efficient indeed and very flexible in her speed range. Another benefit of high aspect ratio hulls that can be maximized w the cat configuration.
When quartering seas do cats have a tendency to stick their props out into the air?
 

Attachments

  • CS hull form.jpg
    CS hull form.jpg
    107.8 KB · Views: 165
Last edited:
Length/beam ratio?

Never had a prop cavitate in any conditions.
 
rjtrane said:
......

We ended up installing parallel hybrid with ZF sail drive from Steyr 75 HP diesels/7 kW electric motors. We needed to reconfigure the trailing section of the bottom to accommodate these legs - not as pretty as original concept. Also, we ended up adding significant weight (diesels aft along with lots of wood and structure), so the flat sections aft were immersed along with the chine and some "ugly" sections above the chine. Top speed with these diesels remained at 9 knots.

I have also attached an "as built" photo showing the aft sections as modified for the sail drive leg. My guess is that this treatment is not unlike the aft sections of other displacement power cats - the flat sections are now well immersed (as indicated by the bottom paint). If we had more HP, I'm sure we'd break the 9 knot barrier and reach speeds in the low teens - unfortunately, our decision to use sail drive precludes more HP as they are limited.
Click to expand...

I proposed a gamefishing-motorsailing cat, and utilized a slightly modified Tennant CS hull form with out-drive-legs.

But as I was intending to use greater HP on the motors I abandoned the conventional 90-degree drive legs for a 'parallel' drive arrangement utilizing silent chain/belts,.....not just a single belt but rather a dual arrangement that would accommodate counter-rotating props.
Tennant_Hull_V_ChainDrive_1000.gif


Tennant Hull V ChainDrive

Chain Drive
YachtForums.Com - View Single Post - New Drive System from Volvo Penta
 
Last edited:
Pacific Harmony

Another big power cat that utilized the CS hull form, albeit modified the bows a little bit....;)
 

Attachments

  • Pacific Harmony before bulbs.jpg
    Pacific Harmony before bulbs.jpg
    57.7 KB · Views: 141
  • Pacific Harmony with bulbs.jpg
    Pacific Harmony with bulbs.jpg
    55.6 KB · Views: 245
Brian. Did you ever build the cat with counter rotating props driven by belts? I love that idea! Was the engineering done on the shafts ?

If course , you can get up to 350 HP Volvo with a stern drive. We used these - twins - in our 42' monohulls - the Island Pilot 395. Speeds in excess of 30 knots on a 32,000 boat.
 
Belt Drive, Chain Drive

rjtrane said:
Brian. Did you ever build the cat with counter rotating props driven by belts? I love that idea! Was the engineering done on the shafts ?
Click to expand...
I did not get that built, nor did we go forward with the 'belt drive' concept. There was no development monies available.

I had started out thinking Kevlar belts, but became convinced that the silent chain was a better idea. Here is a posting (2004) where I was going thru that transition:
YachtForums.Com - View Single Post - New Drive System from Volvo Penta

PYI had come out with a chain drive leg, but only marketed it for a few years. I'll see if I have a few other photos of it. I did collect a lot of info on these silent chains and identified a prime manufacturer I wished to work with on development of such an outdrive leg,...if some development monies should become available.


One sample installation I saved on my older computer
Paradise 60 :: Paradise Yachts

One older spec sheet on the smaller sized unit:
 

Attachments

  • PYI Chain Drive Unit.jpg
    PYI Chain Drive Unit.jpg
    186.6 KB · Views: 135
Last edited:
Rick and trane,
Length to beam ratio = long skinny hull has big numbers like 5-1 ... The favorite of Atkins or 3-1 = fat and wide.

High aspect ratio hulls like cats, canoes and kayaks can easily break the hull speed barrier. I have a powered canoe that goes faster than my 30' trawler. So they are not so limited and have much greater flexibility from a standpoint of speed range.
 
Peter B said:
Parmenter that craft looks a bit like the new Integrity 440 side on…
Click to expand...
I thought so too. Like cutting down the centre, with cat stuff in between.
Benn, Kevin Dick`s Kellick 33 always attracted me, nice no nonsense boat, a modern(ish) Masters 34.
 
The cat from Georgetown, SC. I would think she's one of Tennants designs?
 

Attachments

  • 20130419_151427.jpg
    20130419_151427.jpg
    112.4 KB · Views: 124
  • 20130419_151407.jpg
    20130419_151407.jpg
    127.8 KB · Views: 109
A very nice artistic rendering of another Tennant design. just ran across this in my older files while searching for the drive info.
 

Attachments

  • Rendering of Tennant Cat.jpg
    Rendering of Tennant Cat.jpg
    61.5 KB · Views: 133
Wanted to share a sail cat turned power story about friends boat...
Started life as Viva sailing cat and then he sold rig and built lightweight pod cabin house and added the reverse bow design. Boat is 30ft? powered by twin 15HP. Cruises at 15knots and tops out at 18knots and gets "claimed 8 to 10 MPG" at cruise speed. It does so using the existing non modified sailing cat hulls and experiences no squatting up to 18 knots. Have a look at profile and hull shape. This is probably the 20th boat he has built.
mikepowercat1.jpg

mikepowercat.jpg
 
The nature of the fly bridge on that latest rendering could be adapted to the M52 enhancing her looks.

Brian. Thanks for all the info you've listed. Really enlightening.
 
M52
I like the Viva a lot. And I could USE that boat. I usually don't like the looks of cats but I even like it's looks.

I'm wondering about his other 20 boats?

I'm not nuts about fly bridges on mono hulls but as long as it's light they should work very well on cats. Also because of the shape of their hulls the FB windage shouldn't effect them much either. Hadn't thought about that before but usually don't think about cats. One of the benefits of forums is that you get exposed to things you would normally skirt around and not notice.

Thanks
 
manyboats said:
M52
I'm not nuts about fly bridges on mono hulls but as long as it's light they should work very well on cats. Also because of the shape of their hulls the FB windage shouldn't effect them much either. Hadn't thought about that before but usually don't think about cats. One of the benefits of forums is that you get exposed to things you would normally skirt around and not notice.
Click to expand...
Keep this in mind.

Have you ever been up a mast on a sailboat, or up in the tuna tower of a sportfish. The motion of the vessel gets a little exaggerated up there.

Now make it a multihull and that beam motion can become a lot more 'instantaneous', ....jerky ....fast elevator ride-ish
 
Silent Chain info

rjtrane said:
Brian. Thanks for all the info you've listed. Really enlightening.
Click to expand...
You're welcome.

BTW, you know that 'outside drive leg' could be replaced by a parallel shaft (over/under) arrangement inside the hull, and the subsequent prop shaft exiting the hull in a conventional fashion.

There's a good bit of info on 'silent chains' here
Ramsey Products | Silent Chain Fundamentals

Quite a number of years ago I had contact with another company that was experimenting with both Kevlar belt drives and silent chains for a government program, but they faded away and I lost contact. it was an interesting subject to develop something that would compete with the conventional stern drive.
 
Maltese52 said:
Cruises at 15knots and tops out at 18knots and gets "claimed 8 to 10 MPG" at cruise speed. It does so using the existing non modified sailing cat hulls and experiences no squatting up to 18 knots.
Click to expand...
I notice that doesn't have much rocker in the stern and it does give hints of going flatish as well
But we are talking about cruising boats not day boats.

Swing a decent dinghy and outboard off the back on davits
Throw enough gear on board for a 6 mth cruise with 2 weeks autonomy
Report back.

I guarantee the results will be different.;)
 
Hmmm. Magic Bus is a different approach, for sure. Twin 315's and 26 knots is nothing to scoff at either. I was aboard a 30 minute fuel run of a PDQ 41 last year that obtained an honest 24 and touched 25 knots several times with twin 260 Yanmars in Biscayne Bay. This was at slack tide with virtually no wind, and less than 100 gallons of fuel aboard. After another 100 gallon fill, it still got 23 knots on the way back to Key Biscayne, albeit with a bit of squat.
 

Attachments

  • pdq 41.jpg
    pdq 41.jpg
    84.4 KB · Views: 175
Last edited:
Pdq 41

healhustler said:
.... I was aboard a 30 minute fuel run of a PDQ 41 last year that obtained an honest 24 and touched 25 knots several times with twin 260 Yanmars in Biscayne Bay. This was at slack tide with virtually no wind, and less than 100 gallons of fuel aboard. After another 100 gallon fill, it still got 23 knots on the way back to Key Biscayne, albeit with a bit of squat.
Click to expand...
Those vessels were really nicely finished out, but what always turned me off about them was that VERY high freeboard look with its straight sheer line,....just not attractive in my book.
 
Last edited:
Design Influence, Water Wizard cat

Over on this other subject thread, the subject of the Journey powercat came up, and I was trying to recall the origin of this design, and/or the 'photo vessel' that influenced the hull design.

brian eiland said:
I'm trying to remember the exact circumstances as to the beginning of this project, but it was not Jet Tern, nor Selene that began it. I seem to recall it was several young brokers out on the west coast of the USA that felt a need for a product like this. They contacted that designer who had designed a 'photo catamaran' for that America's Cup involving the big cat and the big tri (over in Spain).

They put the whole project together, then subsequently found the Chinese builder. This all happened before the market crash of 2008 if I recall correctly. Then of course as most of us know the boat market went into recession as well, so I suspected they were going to have a very tough time selling their boats/idea in that atmosphere.
Click to expand...

Here is the vessel design that had a big influence on that hull design, Water Wizard
gallery-waterwizards-01.jpg

Water Wizards Photo Gallery - Morrelli & Melvin | Multihull Design * Engineering * Brokerage

Turns out that 'photo vessel' was a Morrelli/Melvin design based on another's concept
Water-Wizards" / "Ocean Film Boat" is a specially designed craft to reduce the motion of ocean swell and provide a high-quality film and photo platform for the live or recorded [video] coverage of yacht racing. The craft, a concept of Stephen Shidler, was designed to offer the smoothest seaworthiness moving at speeds matching the action of high-performance yacht racing.
Click to expand...

Ocean Film Boat Web Site
 
Story of Journey Cat Beginings

Just found this and thought I would also include some of the text in case it disappears in the future.


Every vision of a new boat has a definitive starting point. This is no exception.

In 2008 we were working with several clients that were all searching for a catamaran with good performance and classic aesthetics. Surprisingly we found that there was nothing in the marketplace that addressed these criteria. After much research and input from current and past customers a preliminary plan was written and presented to our clients and this led to a commitment from one client to build a boat.
Thus the Journey forth began.

Neil Riley, our in-house catamaran specialist, started searching the web for boats, designers, and builders. Slowly our boat started to take shape. Our experience told us there was no long-range production cruising catamarans on the market and the custom-built ones were extremely expensive. This is when we came across “Water Wizards” – a custom-designed and -built 50-foot catamaran with wave-piercing bows built to cruise in the ocean at 30 knots and film sailboat races. This design was not only sea-worthy and stable but extremely fuel-efficient – an eco-friendly platform. It was time to contact the designer.

We then met with Tim Kernan, NA, (company information is in the appendices). We had two major design criteria:

  1. We wanted a long-range, very fuel-efficient cruising catamaran and
  2. We did not want it to look like most other catamarans, boxy and square.
As you can see, we got just what we wanted. We then contracted Kernan Design to complete the boat drawings, so we would be able to present them to builders for the purpose of obtaining a quote for construction costs.

Since plans were being drawn, it was time to find a builder and conduct more research. We found numerous qualified and receptive builders in the US, as the boating market was in a depression. However, the cost for them to produce the boat would place her well above our targeted market price.

Hence, we turned overseas. Again, with a depressed, US boat market we figured we could find some eager builders and we did. We were preparing packages to send to builders in order to obtain quotes for the tooling and building costs when we had a stroke of good fortune. While contacting a model builder in Hong Kong to get a quote, we discovered his consulting service for Westerners in China.

He is William Baycroft of Yacht Consultants, Asia (particulars in appendix). As we discussed needs for a model to display at boat shows, we informed him of our project. He then offered his services, which we gladly accepted. Having a lifetime of experience building boats and many years doing so in China, he was the perfect person to help find a builder.
Neil made numerous trips to China to visit different builders with Mr. Baycroft. We finally settled on one: Jet Tern Marine, the builder of Selene Ocean Trawlers. Not only was the owner, Howard Chen, very enthusiastic about the project, he was sure he could sell a fair number of the 47-foot Journeys in China plus develop a larger version or two.

Backing up a bit, while all of the above was working, we started marketing the boat in January of 2010. We had done a lot of research as to where we should spend our marketing dollars and where to introduce the boat. We decided to go with PassageMaker magazine, as their reputation in the long-range trawler market was superb. They also sponsor numerous Trawler Fests and boat shows for only trawlers across the country. One other reason was that the builder of the 47-foot Maine Cat had invested his marketing dollars in the magazine and sold 6+ boats over a 6-month period.
Click to expand...
Catamarans for Sale - Learn the 47 Long Range Catamaran Story
 
You must log in or register to reply here.

Similar threads

C
2023 Leopard 40 Powercat For Sale
Replies
1
Views
339
Curtis C
C
S
insuring a trawler cruising trawler
Replies
18
Views
2K
Capt Ray
C
B
Ahoy from Eureka, CA
Replies
0
Views
79
Buoyant
B
H
Used, Laid Up Trawler about 50 ft
Replies
23
Views
3K
Hybrid1
H
H
Harborseal New to Trawler Forum
Replies
2
Views
355
Comodave
Comodave

Latest posts

Back
Top Bottom