Engine size when using twins

Marin said:

Originally Posted by psneeld
When you have no specific place to be from day to day....a trip of 5 to 10 miles at 6 knots isn't all that bad.....


True, but.... when your shortest run is 22 miles or so and most of your boating during the year is limited to weekends, an 8-knot boat well and truly sucks.

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Wifey B: And some of us do have places to go and things to do. Not places we have to go but places we want to go.

markpierce said:

Worth saying again ...


Today's run from Vallejo to Benicia/Martinez and return (exercising engine and observing/enjoying nature's and man's doings in Carqinez Strait) averaged 4-plus knots SOG against the current and eight-plus knots with, at about 1.5 gph for 6.3 knots through the water. Weather was cool, but having the pilothouse doors closed kept us comfortable. Pitied the one sailor seen in an open cockpit. ... When buddy-boating with friends, I generally leave earlier so their faster boats can catch up.

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I guess you just wave when sail boats pass you. Maybe when I get old enough I will mellow out and slow down. I still like sailing and powering at speeds faster than my kayak. I can mellow down and relax at 9K but I don't think I could do 6k in a power craft. But I am only 76 maybe at 86 or 90. Good for us that we can do our own thing out on the water.

eyschulman said:

I still like sailing and powering at speeds faster than my kayak. I can mellow down and relax at 9K but I don't think I could do 6k in a power craft. But I am only 76 maybe at 86 or 90..

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Well, when I get up there I suspect that speed will still be important to me. Life's too short and there's too much to see to creep around at 6 or 8 knots. Even at 30 knots we'd never see all the stuff we want to see between here and the top of SE Alaska before we head off to wherever we go boating after this planet. Eight knots ain't gonna cut it up here much longer I think. Our GB's days are numbered........

For those moving from sailboats to trawlers, 7 knots seems like a good speed generally. For those of us moving from 55 knots then we just can't do that. Doesn't mean there's anything at all wrong with 7 knots. Just not us. And like you, Marin, I don't see us ever slowing down to 7 knots. Maybe when we're quite old 12-15. Of course we'd have to keep a fast boat too.

Marin said:

Well, when I get up there I suspect that speed will still be important to me. Life's too short and there's too much to see to creep around at 6 or 8 knots. Even at 30 knots we'd never see all the stuff we want to see between here and the top of SE Alaska before we head off to wherever we go boating after this planet. Eight knots ain't gonna cut it up here much longer I think. Our GB's days are numbered........

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I know you've not been particularly in favor of this. But, that might change. I recommend:

Get a nice condition, well powered 44" Tolly... planning hull... fast as needed! Comfortable, easy to maintain, tough as nails!! Affordable and holds its value. There are plenty to chose from in your PNW area.

I'm finding myself driving slower on the freeway in recent rears, moving at the speed limit and having everyone pass me. ... If I want to take the Coot to Sausalito or Tiburon for a restaurant meal, I take two days for the round trip. If in a hurry to do it in one day, I take the car.

I usually run speeds on hwy where maybe one or two vehicles are going slightly faster - for - cop bait!


I'm well aware what is 360 degrees within site. Old habit - for reasons - LOL!


Couple tricks to keep cops happy:


- Stay off outside lanes
- If you're speeding and cop is seen - instantly slow down. If they are tracking by radar and you abruptly slow soon enough their gun has seconds of confusion and then settles on your reduced speed. Your slowing also shows them you have respect and helps to please the cop.
- Don't often speed in bright red vehicle... attracts cop eyes like red cape attracts a bull!

Perhaps some forum members would prefer this boat over a trawler:

markpierce said:

Perhaps some forum members would prefer this boat over a trawler:

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Wifey B: ME!!!!!!!!!!!!!!!!!!!!!!!!!!

Ok, seriously I would for a day or so, but we did decide we wouldn't enjoy those speeds and that type boat regularly.

Art said:

I usually run speeds on hwy where maybe one or two vehicles are going slightly faster - for - cop bait!


I'm well aware what is 360 degrees within site. Old habit - for reasons - LOL!


Couple tricks to keep cops happy:


- Stay off outside lanes
- If you're speeding and cop is seen - instantly slow down. If they are tracking by radar and you abruptly slow soon enough their gun has seconds of confusion and then settles on your reduced speed. Your slowing also shows them you have respect and helps to please the cop.
- Don't often speed in bright red vehicle... attracts cop eyes like red cape attracts a bull!

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Wifey B: I know this will blow my image. In spite of the fact we have sports cars we never drive more than 5 to 10 mph above the speed limit. We couldn't live with ourselves if extremely high speed on our part led to a death. We also do not under any conditions drink and drive. Guess there goes the party girl, wild and out of control picture you had of me.

Art said:

I know you've not been particularly in favor of this. But, that might change. I recommend:

Get a nice condition, well powered 44" Tolly... planning hull... fast as needed! Comfortable, easy to maintain, tough as nails!! Affordable and holds its value. There are plenty to chose from in your PNW area.

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Already got the "problem" solved, thanks. And as you probably recall, I'm not a fan of Tollys aesthetically. Too cabin-cruisery-looking for me. And not nearly fast enough.

BandB said:

Wifey B: I know this will blow my image. In spite of the fact we have sports cars we never drive more than 5 to 10 mph above the speed limit. We couldn't live with ourselves if extremely high speed on our part led to a death. We also do not under any conditions drink and drive. Guess there goes the party girl, wild and out of control picture you had of me.

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Yo, WB

5/10 mph above speed limit is bout all you can consistently get away with, and that's the extra I average too. 5/10 xtra mph is about how much is realized while letting a one or two "Copper-Stopper" speedsters pull ahead. I agree completely - don't put others' lives in danger on the road for extra speed or otherwise. I don't drink (or smoke wacky tobackie)... so... no problem there ~ ~ ~ ! Lots of fun cruisen in my 67 Wildcat though. Passing in overdrive with 360 hp and near 500 lbs fpt can be a thrill! Only a few thousand miles on completely rebuilt engine - by a renowned professional race car machinist and fine mechanics!!

Marin, I cruise at close to 20 knots now. I'm not retired and my time is precious and I can afford the fuel. And it is kinda nice to have the Cummins synced up and humming at 2400rpms....they sound pretty damn good!

As far as go fast boats go.....for the longest time(and it still may be on the market), during my broad searches of diesel powered boats on YW, a 40 foot Fountain always showed up. It was powered by twin Yanmar 440hp and boasted a fuel burn of 20GPH at 55knots!!!!!! How is that for efficiency??? Anyway, I was always intrigued by that boat..... always thought it was kind of novel.

Art said:

Yo, WB

5/10 mph above speed limit is bout all you can consistently get away with, and that's the extra I average too. 5/10 xtra mph is about how much is realized while letting a one or two "Copper-Stopper" speedsters pull ahead. I agree completely - don't put others' lives in danger on the road for extra speed or otherwise. I don't drink (or smoke wacky tobackie)... so... no problem there ~ ~ ~ ! Lots of fun cruisen in my 67 Wildcat though. Passing in overdrive with 360 hp and near 500 lbs fpt can be a thrill! Only a few thousand miles on completely rebuilt engine - by a renowned professional race car machinist and fine mechanics!!

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Wifey B: In NC only 5. Other places, like 10. Yeah a quick pass or a fast acceleration here and there. Zero to 60 in 3 sec. They say 197 top speed but I'll never freaking know that, they could be making that number up for all I know. 560 hp. And a target car for highway patrol if there ever has been one. So better not go in the fastest pack because if they can only get one, then you're it.

BandB said:

Wifey B: In NC only 5. Other places, like 10. Yeah a quick pass or a fast acceleration here and there. Zero to 60 in 3 sec. They say 197 top speed but I'll never freaking know that, they could be making that number up for all I know. 560 hp. And a target car for highway patrol if there ever has been one. So better not go in the fastest pack because if they can only get one, then you're it.

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WB

560 hp - Ouch! 3 sec 0-60 Fun! Type of auto? Engine cubes? 197 mph at WOT Eeeeekkk!

My 67 Cat has original factory quoted top end of at 148 mph. I had her bury the needle once... lots more to go. I backed off, taint no sense to go faster than that unless on a pro track with pro car - IMO. Cat weighs in at 4.9K lbs.; with recently professionally rebuilt high performance motor, 1/4 tank high test, full size spare tire and Linda and me. Stop watch on measured mile 5.9 sec 0-60. Not too bad for AC'd, power everything, 48 yr old classic "Luxo-Muscle-Car"!

Rebuild engine has <3K miles. Once she gets fully broken in (10 K mi) I plan to take her to a dyno shop and find out what is really being created at her rear wheels. If I want to get a bit more (50 +/- extra hp)... cam, intake manifold, and carb can be modified. Think I'll keep her as is... enough fun already, and, no tune-up hassle!

Art said:

WB

560 hp - Ouch! 3 sec 0-60 Fun! Type of auto? Engine cubes? 197 mph at WOT Eeeeekkk!

!

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Wifey B: 911 Turbo S. It's my dream car. Only put about 4,000 miles a year on it. Yes, I know...way over the top, but it's cute and I like it. Plus we live in the perfect place to drive around topless. The car topless, silly men. Convertible.

BandB said:

Wifey B: Plus we live in the perfect place to drive around topless.

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Plus you live in the perfect place to get skin cancer.

Donsan said:

Plus you live in the perfect place to get skin cancer.

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Wifey B: You are correct and it's freaking scary so I'm very careful. Lay out under the flybridge top or at home under the patio cover. Swim after dark a lot. And high SPF lotion repeated many times a day. We look at each other and just grab the lotion and put more on. Besides sort of enjoy it. But we avoid sunburn like the plague, because it is. Unfortunately, we have members here who have told the danger from personal experience.

Relative to the title of the original post the size of engines or engine should have absolutely nothing to do w the number of engines employed.

Unless suitable power cannot be found in the number of engines that is needed or preferred.

A boat requiring 200hp should have 200hp irregardless of the number of engines.

manyboats said:

Relative to the title of the original post the size of engines or engine should have absolutely nothing to do w the number of engines employed.

Unless suitable power cannot be found in the number of engines that is needed or preferred.

A boat requiring 200hp should have 200hp irregardless of the number of engines.

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Actually I have come across a weird situation where that rule did not seem to work. On some of the narrow express type boats with IPS drives they are using three engines because to get more HP out of the two there is not enough room in the hull for larger engines side by side so they dump a third motor fore or aft on the mid line. The New MJM Zern 50 ft express offers the three motor option. With these fast boats it comes down to how much HP(speed) the buyer wants not so much what the hull calls for.

Yes and I've seen outboards w five or so engines on their sterns. But for the most part engine power comes first and then the number required to get the job done.

eyschulman said:

Art the SD seems to fit my boat best without using buttocks angles in the definition.

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For those that are interested in design and especially the QBBL there is a thread on BoatDesign.net under "boat design" that speaks to the Quarter Beam Buttock Line (QBBL). Most of the guys on BD.net know a lot more about it than me.

I believe one can browse there w/o joining.

manyboats said:

For those that are interested in design and especially the QBBL there is a thread on BoatDesign.net under "boat design" that speaks to the Quarter Beam Buttock Line (QBBL). Most of the guys on BD.net know a lot more about it than me.

I believe one can browse there w/o joining.

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Eric - tried to locate BD.net That correct link address?

Art said:

Eric - tried to locate BD.net That correct link address?

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Try boat design . net Art

Sorry Art,
Abbreviations and acronyms are a PITA .... HAHA. I usually use the whole expression before going to the acronym on a thread cuz I hate that mystery stuff.
Good forum to spend time on. Much bigger than TF. They have threads on almost everything. Lots of smart guys and pics of the blow you away catergory and the links will take you around the world.

manyboats said:

Sorry Art,
Abbreviations and acronyms are a PITA .... HAHA. I usually use the whole expression before going to the acronym on a thread cuz I hate that mystery stuff.
Good forum to spend time on. Much bigger than TF. They have threads on almost everything. Lots of smart guys and pics of the blow you away catergory and the links will take you around the world.

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Thanks, Eric / Craig... I'll try to look into that "BD" site. I have hard time fitting in this site alone between doings all day and eve.

Art you're a young feller but I managed while on a road trip to Edmonton Alberta. Haf'ta find my wi-fi too.
Dirtiest white car you've ever seen and slight sheet metal damage from ice. The Beluga Jetta's no longer new.

Rocks,

I think that Gulfstar was well bought into using Perkins engines, the 36 in this year had 4 power options that I know of a single 4.154 or a 4.236 and twins in the same engine. The next smaller 4 cylinder Perkins is the 4.108 at about 50HP. I have the same boat as you but have twin 4.236. I run 7 knots at 1800-1900 RPM. I can get 9 knots at WOT, but I don't push my 1975 vintage engines that hard for more than a min or two.

On The Rocks said:

Just curious why most twin engine displacement trawlers have engines that are the same hp as would be used if the boat had a single screw?

For example my 36 fd trawler has two 62 hp engines. Since 62 hp is more than enough power to cruise at hull speed wouldn't it be more efficient to have two 31 hp engines and still be able to cruise at hull speed?

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Gulfstar 36,
Great boat.
The Perkins 4-108/7 is 36hp at 3000rpm. Never seen one run at any other rpm on a boat. I think they were in taxi cabs in England making 50hp at 4000rpm.
Nice to see that some manufactures offered a range of engine options. If I had one I'd probably opt for the twin 108s. Rather have a newer engine though. I have a 4-107 Mitsu in my 30' Willard. It's a very good but not particularly modern.

" The GB36 had only one configuration that made sense and that was a twin FL 120hp at 8 to 10 knots. "
Manyboat, with all due respect I disagree. I owned a '77 GB 36 for many years with a single FL 120. It was perfect for my usage--and made a lot of sense in terms of ease of maintenance, economy, etc.
Dawdler