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Old 10-21-2015, 06:53 AM   #181
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Krogen put twins on a big hull type that usually is a single and considered by most to be a long range boat. Do you honestly think Krogen offered the twin thinking it was inefficient?
Eric

I had heard that the twin engine arrangement for the 58 was to provide a lower draft option for those who were concerned about the boat's draft when going to the Bahamas.

The twin engine option reduces the draft by a full foot from 6' 4" to 5' 4".
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Old 10-21-2015, 07:31 AM   #182
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GB36s built here by Riviera usually had twin Cummins 5.9L engines,some had Volvo twin 165s.

GBs built by Riviera?

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Old 10-21-2015, 07:44 AM   #183
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In this thread's posts, regarding high value boat builders, I've read of Volvo engines being factory originals. For years, in other threads' posts I'd learned of Volvo's being difficult to get service upon as well as poor Volvo factory assistance and expensive Volvo parts that take too long to get delivered. Therefore I've shied away from any Volvo powered boat.


What gives?? Am I missing something here?


Why would good boat builders offer Volvo engines if their upkeep is as difficult as I'd previously learned from other threads? Are Volvo engines superior performers when they are running correctly and do they not often need service?


Just wondering!


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Old 10-21-2015, 07:50 AM   #184
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Greetings,
Mr. A. I was surprised at how many NEW builds that I've seen at recent boat shows have Volvo engines and have been wondering exactly the same thing. The first and only reason that comes to mind is that Volvo is the most cost effective for builders to install in their vessels (for the builders). No builders that I am aware of are the least bit concerned about aftermarket, off warranty "problems".
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Old 10-21-2015, 08:44 AM   #185
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Quote:
Originally Posted by Art View Post
In this thread's posts, regarding high value boat builders, I've read of Volvo engines being factory originals. For years, in other threads' posts I'd learned of Volvo's being difficult to get service upon as well as poor Volvo factory assistance and expensive Volvo parts that take too long to get delivered. Therefore I've shied away from any Volvo powered boat.


What gives?? Am I missing something here?


Why would good boat builders offer Volvo engines if their upkeep is as difficult as I'd previously learned from other threads? Are Volvo engines superior performers when they are running correctly and do they not often need service?


Just wondering!


Art
Toyota brought in ' just in time ' production methods on their car assembly lines.

Volvo brought in ' pay us when you get paid' deals for boat builders.
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Old 10-21-2015, 10:07 AM   #186
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This is a popular operational mode for a lot of Grand Banks boats in our harbor, particularly in the big charter fleet. They bomb on up to Desolation Sound at 14-16 knots in a day or two, a trip that takes us some four days at 8 knots, cruise around at 8 knots or so enjoying the place, and then bomb on home.

There's a big market here for boats that can do that.
......
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Old 10-21-2015, 11:19 AM   #187
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Diesel fuel does not contain all that much more energy than gasoline.
http://www.diffen.com/difference/Diesel_vs_Petrol
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“Energy Content of petrol vs diesel
Gasoline contains about 34.6 megajoules per litre (MJ/l)while diesel contains about 38.6 megajoules per litre.”
True. Here are some other reasons why diesel engines are typically more efficient than gasoline engines.

-Diesels have a much higher compression ratio than gassers.

-Diesels have lower pumping losses. Unless operating at full throttle, a gas engine will have a throttle that restricts the flow of air into the engine. The energy required to pump this air past this restriction is not insignificant.

-Diesels operate in a "lean" air-fuel condition where as a gas engine usually operates with rich air fuel mixture (the unburnt, evaporating fuel is important for controlling temperature). Typically, a gas engine will be set up to run increasingly rich as power is increased.

Some modern automobile gas engines are running "lean burn technology". Also, some people (me) run their aircraft "lean of peak" at power settings of less than 60 or 70 percent.

Are any gasoline marine engines set up to run lean?

Steve
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Old 10-21-2015, 11:35 AM   #188
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I have seen the fuel burn numbers for comparing single to twin installs for the KK 52, Nordic Tug 52 and Nordhavn 55. Surprisingly close dependent upon speed but my takeaway in all 3 cases was a 10% differential favoring the single.
Efficiency of the larger prop on the single no doubt comes into play. Properly over-prop the twins or add larger variable pitch props and that number will become even smaller.
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Old 10-21-2015, 12:51 PM   #189
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cafesport

My observations are that the ER in a twin N55 was quite workable with engines one JD size down and get home eliminated. What are your thoughts?

Sun chaser, more spacious and workable for several reasons. Engines are a foot shorter in height and length no dry stack and a different tankage system.


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Old 10-21-2015, 01:01 PM   #190
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Steve wrote on post #187;
"-Diesels operate in a "lean" air-fuel condition where as a gas engine usually operates with rich air fuel mixture (the unburnt, evaporating fuel is important for controlling temperature). Typically, a gas engine will be set up to run increasingly rich as power is increased."

Diesels run at 50-1 and 60-1 fuel-air ratios at idle. They are very close to gas engines only at WOT. Consequiently they use little fuel at mid power.
Related to this is the fact that at low power they run w low fuel levels they also have low heat levels. That's the source of the issue of potential problems at low load w diesels. With so little fuel injected you're not going to fry any eggs on exhaust manifolds .. at low loads.

Interestingly though at full bore they (gas and diesel) engines burn about the same amount of fuel mostly because their fuel ratio is about the same .. 15-1.
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Old 10-21-2015, 02:08 PM   #191
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Sun chaser, more spacious and workable for several reasons. Engines are a foot shorter in height and length no dry stack and a different tankage system.
I was surprised similarly by the plans for "quite workable' ER space in the KK 52 with smaller twins and the get home not there.

It would seem from the space standpoint the same well designed hull with twins vs a larger single with get home, is not a shoe box stuffed with Imelda's closet.

Also, two years ago I was considering a new design Nordhavn 52 with an aft cabin arrangement. The ER space with twin 4045s was amazing when compared to the traditional N47/52, Nordhavn agreed. Those plans are now available on the Nordhavn website for those interested.
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Old 10-21-2015, 03:29 PM   #192
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GBs built by Riviera?

-Chris
Hi Chris,

Bruce K is correct , under license here in Australia Riviera did build theGB 36 ,and I think from memory GB 42's Europa style, but with out the covered side and rear decks. They were quite popular in the 80's early 90's from here, still got a few here in Newport Sydney and still bring good prices. They were quite fast compared to the traditional GB's

Cheers Chris D Liberty
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Old 10-21-2015, 03:47 PM   #193
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Interestingly though at full bore they (gas and diesel) engines burn about the same amount of fuel mostly because their fuel ratio is about the same .. 15-1.
Thermodynamic efficiency is largely influenced by compression ratio, not so much by fuel/air ratio. Three things really nail gasser efficiency: Lower CR by design. And CR effectively drops further when at part throttle. And at full power, timing is reduced and fuel/air mix richened to limit detonation and control piston/head/valve temps.

Throttling the inlet air is an energy loss, but the larger effect in most areas of the map is driven by the lower effective compression ratio. At 10" HG manifold vacuum, the piston does not start compressing anything until a third of the way up. So a 9:1 CR turns into a 6:1, roughly. That's the main reason gasser efficiency is so bad at light load.

I'm amazed we use gas engines as much as we do. Good for chainsaws, lawnmowers, weedeaters, outboards and fun weekend cars. Anything where efficiency matters should be diesel. IMHO...
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Old 10-21-2015, 04:35 PM   #194
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Hi Chris,

Bruce K is correct , under license here in Australia Riviera did build theGB 36 ,and I think from memory GB 42's Europa style, but with out the covered side and rear decks. They were quite popular in the 80's early 90's from here, still got a few here in Newport Sydney and still bring good prices. They were quite fast compared to the traditional GB's

Interesting, never knew that any were built outside the normal Asian yards...

-Chris
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Old 10-21-2015, 05:49 PM   #195
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Thanks Ski for #193.

This new stuff gets better all the time. Love the new Yanmar OB and I can't believe the millage my 2013 Accord gets and the turbo Jetta that came before it. A CVT type transmission may work wonders in a boat as the advantages of a straight drive and a variable pitch prop could perhaps both be realized. The CVT probably would be more expensive than pod drives and vari-pitch props.

I've always thought a twin w engines close in by the keel one ahead of the other (staggered if you will) would solve the space problem in the engine room/compartment of twin engined boats. Anybody ever heard of one? No new technology would be required.


With the staggered fore and aft twin .. propellers could be very close to the keel offering grounding capabilities basically the same as a single. A slightly longer single rudder would be mostly out of the prop wash except when turning so it should be more efficient than a single. No prop wash pulling the rudder backwards. The average handy man could do this to an existing boat too.
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Old 10-21-2015, 06:38 PM   #196
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GBs built by Riviera?

-Chris
Here`s one listed for sale:Used Grand Banks 36 for Sale | Boats For Sale | Yachthub
Check the pic of the electrical switchboard.
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Old 10-21-2015, 06:54 PM   #197
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I just learned the other week that there is a Riviera Grand Banks 36 in our harbor. Took a look at it the other weekend and it's just like the one in Bruce's link. Don't know what it has for engines. I met the owner but this was before I was told what his boat actually is. The configuration is what Grand Banks would have called a Sedan.
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Old 10-21-2015, 08:14 PM   #198
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We should all have a camera handy. Interesting sightings happen almost constantly.
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Old 10-21-2015, 08:38 PM   #199
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The fellow who owns the Riviera GB36 is from the SFO Bay area, apparently. I was introduced to him by another GB36 owner we have come to know who's in the same part of the marina we are. The fellow with the Riviera GB is a few slips down from him.

So we were standing there talking--- this was a few weeks ago and I was on my way back down the main dock from fetching our groundpower cord from our slip to take to our boat which we had just parked on the yard's Travelift dock after our attempt to sink it out in the bay--- and after we were introduced the Riviera owner asked if our boat was the older GB a few docks farther out. I said yes it was, that's it over there, and pointed across to the Travelift dock. He looked over and said, "I know that boat. It's from San Francisco Bay, right? It used to be named Westwind."

I said that it had had three or four owners before us but the only previous names I remembered were Grand Destiny (when we bought it in Alameda) and Christopher Robin (when it had been in Sausalito).

He said, "It has that really neat dropdown radar mount over the helm, right?" I said, "Yes, it does." He said, "That's the Westwind. I remember that mount. I've never seen another GB with that type of mount."

He took off and that's when my friend told me that this guy had a GB36 Riviera and that it's the only one in the US. Also according to my friend, the Riviera owner knows or knows about just about every Grand Banks in the US, particularly the older ones so it was no surprise that he knew our boat from years past.

When I walked over to look more closely at the Riviera the next weekend at first it just looked like a stock GB36 Sedan. But then I started noticing different details, one of which is the pair of blue stripes around the base of the flying bridge instead of the usual teak trim.
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Old 10-21-2015, 08:54 PM   #200
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I believe the 36 was the only GB Riviera built under license. Riv construction is quite good, though I was told by a broker that both the Aust. and Singapore built boats get osmosis, one gets occasional big blisters, the other tiny ones all over, I can`t recall which is which.
The original (not the current)principal of Riviera was Bill Barry Cotter, now of Maritimo. Before Riviera, he ran Mariner, and as well as its planing cruisers it sold trawlers under the Mariner name, 36, 39 and a 46,most likely built in in Asia, they look somewhat C&L. The 36 and 39s look nice boats, there was also a sundeck 39, Lehmans were fitted.
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