|
|
10-14-2015, 06:16 PM
|
#121
|
Guru
City: Meydenbauer Bay Yacht Club
Vessel Name: Lulu (Refugio sold)
Join Date: Mar 2012
Posts: 1,284
|
Quote:
Originally Posted by O C Diver
Yup, and all that space on both sides of the engine.
|
Yeah, all that space is just wasted. Unless you want to service the engine. Again, I understand some owners consider that "optional".
Oh, and then there's the ability to add sound insulation when the engine sits lower - and there's only one of them. But hey, if you're really proud of how your engines sound and want to share that with your passengers, then that wouldn't be a feature you'd want.
And doubling the number of hull penetrations - everyone knows that you increase seaworthiness by punching additional holes in your boat. That's just common sense, right?
Keith
__________________
Keith
|
|
|
10-14-2015, 06:18 PM
|
#122
|
Master and Commander
City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,559
|
Quote:
Originally Posted by sunchaser
Tough game to play Mark. A sad one too. Became familiar with the Pilatus story and airplane a few years through a nephew who regularly flew one. While he was doing that gig another one went down in MT with 14 on board. Unfortunately sad stories of this kind involving small airplanes never seem to let up.
|
You're confusing me. The Hellcat I'm referring to is a WWII fighter plane with a single pilot and no others aboard.
__________________
Kar-KEEN-ez Koot
|
|
|
10-14-2015, 07:53 PM
|
#123
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
Quote:
Originally Posted by refugio
Well I like a big rudder too, but that's just me - others may not be as picky about what direction they're going.
I'm also kinda partial to a low COG and rolling moment. And a flat shaft angle, and a big prop, well down in the water. Again, that's just me - others might be happy squirreling along with marginal efficiency and control.
Oh, and I like large tanks. You know, for range.
Keith
Quote:
Originally Posted by sunchaser
Keith you don't know how many people you have just PO'd with these truisms.
|
Noten psses me off regarding other boater's desires, needs, haves, wants, or suggestions.
Hope whatever I mention does not pss any others off. However, if any of what I post does... oh well, grow up! This is just a marine forum. Pretty darn good one at that - IMO.
Happy Trawler Forum Daze! - Art
|
|
|
10-16-2015, 11:46 PM
|
#124
|
Guru
City: PNW
Vessel Model: 1976 Californian Tricabin LRC
Join Date: May 2011
Posts: 1,860
|
Well. . . .
I haven't been on the forum for about a month.
But I see I haven't really missed a thing....
__________________
Larry B
Careful . . .I Have a Generator and I'm not afraid to use it !
|
|
|
10-17-2015, 02:46 AM
|
#125
|
Guru
City: Meydenbauer Bay Yacht Club
Vessel Name: Lulu (Refugio sold)
Join Date: Mar 2012
Posts: 1,284
|
Quote:
Originally Posted by Edelweiss
Well. . . .
I haven't been on the forum for about a month.
But I see I haven't really missed a thing....
|
What a coincidence! Neither have we
Keith
__________________
Keith
|
|
|
10-17-2015, 05:13 AM
|
#126
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
|
|
|
10-17-2015, 06:55 AM
|
#127
|
Guru
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 12,834
|
Quote:
Originally Posted by Art
|
Have we settled the point that singles are better and people with twins are looking for more of a better thing?
Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
|
|
|
10-17-2015, 10:17 AM
|
#128
|
Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
|
Singles are better if that's all you can afford.
__________________
Eric
North Western Washington State USA
|
|
|
10-17-2015, 10:42 AM
|
#129
|
Guru
City: San Diego
Vessel Name: Circuit Breaker
Vessel Model: 2021..22' Duffy Cuddy cabin
Join Date: Oct 2007
Posts: 6,691
|
You know...that emoticom really hits home doesn't it?
__________________
Done with diesel power boats! Have fallen in love with all electric!
|
|
|
10-17-2015, 10:44 AM
|
#130
|
Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
|
Quote:
Originally Posted by manyboats
Singles are better if that's all you can afford.
|
Exactly.
I'm surprised nobody has mentioned that twins use nearly double the fuel at displacement speeds.
Rule of thumb:
32'/6 tons/ single[200hp] 2 gals/hr@ 7 kts: 3-4 mpg.
32'/6-7 tons/twin[2x200hp] 4gals/hr@ 8kts: 2 mpg or less.
__________________
Peter.
|
|
|
10-17-2015, 12:50 PM
|
#131
|
Guru
City: Sarasota/Ft. Lauderdale
Join Date: Apr 2014
Posts: 5,438
|
Quote:
Originally Posted by refugio
And doubling the number of hull penetrations - everyone knows that you increase seaworthiness by punching additional holes in your boat. That's just common sense, right?
|
I find all this worry about extra hull penetrations amusing. It's really such a none issue. And of course twin engines don't double the total hull penetrations in a vessel compared to a single. They add like what, two?
There are plenty of good reasons to choose a single engine over a twin. But worrying about added hull penetrations isn't really one of them.
|
|
|
10-17-2015, 01:10 PM
|
#132
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
Have we settled the point that singles are better and people with twins are looking for more of a better thing?
Ted
Quote:
Originally Posted by manyboats
Singles are better if that's all you can afford.
|
Eric and Ted - You two = "Twins"... in the way you calculate things - LOL - Art
|
|
|
10-17-2015, 01:27 PM
|
#133
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
Quote:
Originally Posted by Rustybarge
Exactly.
I'm surprised nobody has mentioned that twins use nearly double the fuel at displacement speeds.
Rule of thumb:
32'/6 tons/ single[200hp] 2 gals/hr@ 7 kts: 3-4 mpg.
32'/6-7 tons/twin[2x200hp] 4gals/hr@ 8kts: 2 mpg or less.
|
You better calc that again!
Twins (same exact engines as the single in same exact boat as the single) are not twice fuel consumption at displacement speed with both engines running and needing less hp each than the single needs to reach speed. Especially when you cruise at or under full displacement speed with one twin shut down. Also, twins are ok in a full displacement hull but really not needed... although they do serve for spare engine and improved close quarters maneuverability.
Twins can become quite useful on SD hulls and very useful on Planing hulls.
Cheers! - Art
|
|
|
10-17-2015, 01:48 PM
|
#134
|
Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
|
Quote:
Originally Posted by Art
You better calc that again!
Twins (same exact engines as the single in same exact boat as the single) are not twice fuel consumption at displacement speed with both engines running and needing less hp each than the single needs to reach speed. Especially when you cruise at or under full displacement speed with one twin shut down. Also, twins are ok in a full displacement hull but really not needed... although they do serve for spare engine and improved close quarters maneuverability.
Twins can become quite useful on SD hulls and very useful on Planing hulls.
Cheers! - Art
|
That's all very well in your Tolly with gass engines that don't mind idling along at 500 revs...!
Given that a big diesel will need a few revs/load not to glaze the cylinders, a twin 200 HP boat would probably have to use 1200-1500revs which will burn at least 2 gal per engine.
Of course you could cruise with one engine, but figures I've seen on the boat design forum show virtually no gain in mpg because of prop drag....
The big question: has anyone got a 32' or larger twin engined trawler that can beat 2 mpg?
__________________
Peter.
|
|
|
10-17-2015, 02:28 PM
|
#135
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
Quote:
Originally Posted by Rustybarge
That's all very well in your Tolly with gass engines that don't mind idling along at 500 revs...!
Given that a big diesel will need a few revs/load not to glaze the cylinders, a twin 200 HP boat would probably have to use 1200-1500revs which will burn at least 2 gal per engine.
Of course you could cruise with one engine, but figures I've seen on the boat design forum show virtually no gain in mpg because of prop drag....
The big question: has anyone got a 32' or larger twin engined trawler that can beat 2 mpg?
|
Yup – Me… that of course is… if our simple to maintain and inexpensive to own or replace gasoline engines are allowed into this discussion!
We get 2.75 to 3 nmpg at 5 +/- knots by running either engine at well under 2k rpm with one shut down and left in freewheel-prop due to that being OK with BW Velvet Drive trans.
With twins running us at 6.5 to 7 knots, i.e. just below hull speed (displacement-running hull speed on our boat calcs at 7.58 knots) we get close to 2 nmpg
Cruising on full plane at 16 to 17 knots we get 1 +/- nmpg.
WOT at 22 to 23 knots = OMG nmpg
|
|
|
10-17-2015, 02:31 PM
|
#136
|
Guru
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48 (sold)
Join Date: Apr 2008
Posts: 10,186
|
Quote:
Originally Posted by Rustybarge
Exactly.
I'm surprised nobody has mentioned that twins use nearly double the fuel at displacement speeds.
Rule of thumb:
32'/6 tons/ single[200hp] 2 gals/hr@ 7 kts: 3-4 mpg.
32'/6-7 tons/twin[2x200hp] 4gals/hr@ 8kts: 2 mpg or less.
|
Well there you go, proof positive of something
|
|
|
10-17-2015, 03:04 PM
|
#137
|
Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
|
Quote:
Originally Posted by Art
Yup – Me… that of course is… if our simple to maintain and inexpensive to own or replace gasoline engines are allowed into this discussion!
We get 2.75 to 3 nmpg at 5 +/- knots by running either engine at well under 2k rpm with one shut down and left in freewheel-prop due to that being OK with BW Velvet Drive trans.
With twins running us at 6.5 to 7 knots, i.e. just below hull speed (displacement-running hull speed on our boat calcs at 7.58 knots) we get close to 2 nmpg
Cruising on full plane at 16 to 17 knots we get 1 +/- nmpg.
WOT at 22 to 23 knots = OMG nmpg
|
5 kts is snail pace!!!
Sorry forgot to say at 7 kts in a single screw; anything slower is like watching paint dry!
Your numbers look like 2 mpg....
__________________
Peter.
|
|
|
10-17-2015, 03:07 PM
|
#138
|
Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
|
Quote:
Originally Posted by sunchaser
Well there you go, proof positive of something
|
Yep, that twin engines use x2 fuel consumption because you have to use higher revs to keep engines working well and that means 7-8 kts.
__________________
Peter.
|
|
|
10-17-2015, 03:23 PM
|
#139
|
Guru
City: Cape May, NJ
Vessel Name: Irish Lady
Vessel Model: Monk 36
Join Date: Dec 2007
Posts: 4,964
|
Quote:
Originally Posted by Art
We get 2.75 to 3 nmpg at 5 +/- knots by running either engine at well under 2k rpm with one shut down and left in freewheel-prop due to that being OK with BW Velvet Drive trans.
With twins running us at 6.5 to 7 knots, i.e. just below hull speed (displacement-running hull speed on our boat calcs at 7.58 knots) we get close to 2 nmpg
|
Thats incredible! What do you use to measure flow?
With twin 5.7L Crusader gas on a 29' Phoenix and a calibrated Floscan, on one engine, the best I could ever get was 5 gph at 1600 rpm for 5 knots for 1 nmpg.
|
|
|
10-17-2015, 03:25 PM
|
#140
|
Guru
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
|
Quote:
Originally Posted by Rustybarge
5 kts is snail pace!!!
Sorry forgot to say at 7 kts in a single screw; anything slower is like watching paint dry!
"....
|
But, But... running w/ a 3 knot current doing 5 knots through water surface = 8 knots OL speed -
Anyway... With our planning hull Tolly... we like to cruise 16 to 17 knots on full plane. Over twice as fast as the top FD hull speed for same size boats. As you know "Time Is Money!" And... although, as you say, " 5 kts is snail pace"... so is 7 knots simply a crawl for us. We only go slow when we want to; rather than because we always have to!
|
|
|
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Trawler Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|