Reply
 
Thread Tools Search this Thread Display Modes
 
Old 12-16-2013, 09:13 AM   #181
Senior Member
 
rjtrane's Avatar
 
City: Palmetto Bay
Vessel Name: Sunshine
Vessel Model: Island Pilot DSe 12m Hybrid
Join Date: Apr 2013
Posts: 268
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.
Attached Thumbnails
DSe_Sunshine_AftSections.jpg   DSe_Sunshine_CGI_Profile.jpg   DSe_Sunshine_CGI_Aft34.jpg   DSe_Sunshine_SeaTrialsZhuhai.jpg  
__________________
Reuben Trane
"Sunshine" - Island Pilot DSe 12m
rjtrane is offline   Reply With Quote
Old 12-16-2013, 12:00 PM   #182
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
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?
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 12-16-2013, 01:31 PM   #183
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
CS Hull Form

Another view of what Tennant referred to as the CS hull form (canoed stern)
[PCW] CS hull form

Malcolm Tennant Multihull Design Ltd - About


...here is a good article of his, with some photos of just some of the vessels that made use of this hull design
Multihulls
Attached Thumbnails
CS hull form.jpg  
brian eiland is offline   Reply With Quote
Old 12-16-2013, 01:40 PM   #184
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
Quote:
Originally Posted by manyboats View Post
Another benefit of high aspect ratio hulls that can be maximized w the cat configuration.

What's that mean?
RickB is offline   Reply With Quote
Old 12-16-2013, 02:14 PM   #185
Senior Member
 
rjtrane's Avatar
 
City: Palmetto Bay
Vessel Name: Sunshine
Vessel Model: Island Pilot DSe 12m Hybrid
Join Date: Apr 2013
Posts: 268
Length/beam ratio?

Never had a prop cavitate in any conditions.
__________________
Reuben Trane
"Sunshine" - Island Pilot DSe 12m
rjtrane is offline   Reply With Quote
Old 12-16-2013, 02:35 PM   #186
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
Quote:
Originally Posted by rjtrane View Post
Length/beam ratio?
Yeah, of a single hull at that probably. Should'a just said so instead of making up new terms. Way to much of that already.
RickB is offline   Reply With Quote
Old 12-16-2013, 02:38 PM   #187
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
Quote:
Originally Posted by rjtrane View Post
......

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.
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.
Click image for larger version

Name:	Tennant_Hull_V_ChainDrive_1000.gif
Views:	268
Size:	86.1 KB
ID:	25751


Tennant Hull V ChainDrive

Chain Drive
YachtForums.Com - View Single Post - New Drive System from Volvo Penta
brian eiland is offline   Reply With Quote
Old 12-16-2013, 03:41 PM   #188
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
Pacific Harmony

Another big power cat that utilized the CS hull form, albeit modified the bows a little bit....
Attached Thumbnails
Pacific Harmony before bulbs.jpg   Pacific Harmony with bulbs.jpg  
brian eiland is offline   Reply With Quote
Old 12-16-2013, 06:51 PM   #189
Senior Member
 
rjtrane's Avatar
 
City: Palmetto Bay
Vessel Name: Sunshine
Vessel Model: Island Pilot DSe 12m Hybrid
Join Date: Apr 2013
Posts: 268
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.
__________________
Reuben Trane
"Sunshine" - Island Pilot DSe 12m
rjtrane is offline   Reply With Quote
Old 12-16-2013, 09:14 PM   #190
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
Belt Drive, Chain Drive

Quote:
Originally Posted by rjtrane View Post
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 ?
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:
Attached Thumbnails
PYI Chain Drive Unit.jpg  
brian eiland is offline   Reply With Quote
Old 12-16-2013, 09:48 PM   #191
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
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.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 12-16-2013, 09:56 PM   #192
Guru
 
BruceK's Avatar
 
City: Sydney
Vessel Name: Sojourn
Vessel Model: Integrity 386
Join Date: Oct 2011
Posts: 13,333
Quote:
Originally Posted by Peter B View Post
Parmenter that craft looks a bit like the new Integrity 440 side on…
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.
__________________
BruceK
2005 Integrity 386 "Sojourn"
Sydney Australia
BruceK is offline   Reply With Quote
Old 12-16-2013, 10:00 PM   #193
Guru
 
Daddyo's Avatar
 
City: Cruising East Coast US
Vessel Name: Grace
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 2,420
The cat from Georgetown, SC. I would think she's one of Tennants designs?
Attached Thumbnails
20130419_151427.jpg   20130419_151407.jpg  
__________________
Cruiser
Esse Quam Videri
Daddyo is offline   Reply With Quote
Old 12-16-2013, 10:20 PM   #194
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
A very nice artistic rendering of another Tennant design. just ran across this in my older files while searching for the drive info.
Attached Thumbnails
Rendering of Tennant Cat.jpg  
brian eiland is offline   Reply With Quote
Old 12-16-2013, 10:45 PM   #195
Guru
 
Daddyo's Avatar
 
City: Cruising East Coast US
Vessel Name: Grace
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 2,420
Isn't that Domino?
__________________
Cruiser
Esse Quam Videri
Daddyo is offline   Reply With Quote
Old 12-16-2013, 11:25 PM   #196
Senior Member
 
Parmenter's Avatar
 
City: Brisbane
Vessel Model: 49ft 11inch catamaran-trawler
Join Date: Oct 2013
Posts: 204
Quote:
Originally Posted by Daddyo View Post
Isn't that Domino?
Sure is
http://www.hallmarinedesign.com/2_ma...ower-catamaran
Parmenter is offline   Reply With Quote
Old 12-17-2013, 12:33 AM   #197
Veteran Member
 
Maltese52's Avatar
 
City: Los Angeles
Vessel Model: Maltese 52
Join Date: Dec 2013
Posts: 44
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.
Click image for larger version

Name:	mikepowercat1.jpg
Views:	199
Size:	110.0 KB
ID:	25774

Click image for larger version

Name:	mikepowercat.jpg
Views:	184
Size:	97.5 KB
ID:	25773
Maltese52 is offline   Reply With Quote
Old 12-17-2013, 06:56 AM   #198
Senior Member
 
rjtrane's Avatar
 
City: Palmetto Bay
Vessel Name: Sunshine
Vessel Model: Island Pilot DSe 12m Hybrid
Join Date: Apr 2013
Posts: 268
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.
__________________
Reuben Trane
"Sunshine" - Island Pilot DSe 12m
rjtrane is offline   Reply With Quote
Old 12-17-2013, 03:13 PM   #199
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
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
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 12-17-2013, 03:48 PM   #200
Guru
 
brian eiland's Avatar
 
City: St Augustine, FL
Vessel Name: RunningTide
Vessel Model: 37 Louisiane catamaran
Join Date: Jul 2013
Posts: 930
Quote:
Originally Posted by manyboats View Post
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.
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
brian eiland is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 02:25 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012