Re: [PCW] Power-Cats and the Volvo IPS or MerCruiser Zeus Drive systems
DISCLAIMER: This letter written by a catamaran dealer.
Hello power-cat fans,
Here's a question (especially to the cat designers and builders who read this site) regarding a pair of new propulsion systems. I'm wondering if any of you know of any power cats that are offering (as standard or optional equipment) either of the new "pod-drive" systems? That is, either (a) the Volvo Penta IPS (Inboard Propulsion System), distinctive for its forward-facing props, or (b) the Cummins MerCruiser Zeus Drive (aft-facing props) system?
As a catamaran dealer, I've just happened upon the most clear-reading and understandable article about these two systems that I've seen thus far. The article, "The Pod-Drive Revolution" (by Chuck Husick) is in the newest issue (Jan/Feb 2008) of "POWER CRUISING" magazine. The purported benefits (lighter weight, less draft, no rudders, usually undetectable exhaust fumes, quicker pick-up performance, no need for muffler, or water-intake thru-hulls, 20% better fuel consumption, etc.) are, understandably, appealing. But I'm wondering if there's anything about the catamaran design that presents a possible drawback to this new propulsion system? The fact that some major monohull yacht builders (Grand Banks' 41 Heritage, Legacy Yachts and Sabre Yachts) are now employing one or the other of these 2 systems proves there's growing (and serious) support.
So, any cat lovers out there, designers/builders or not, who have any first-hand feedback about either of these systems?
Thanks in advance,
Rod Gibbons
Cruising Cats USA
Seattle, Portland, Oakland, Hawaii
Rob,
We have looked at these motors and they certainly have many
advantages, except
one which is important to cats generally, weight distribution.
IPS 350 (260hp) weighs 790kg
Yanmar 6BY220Z (260hp) with gear 365kg
IPS 600 (435hp) weighs 910kg
Yanmar 6LY28STP (440hp) with gear weighs 558 kg
Times that by 2 motors and fitted onto the stern of the boat, equals
excessive.
Tim Jordaan
----- Original Message -----
From: rodgibbons@mindspring.com
To: power-catamaran@lists.samurai.com
Sent: Friday, December 28, 2007 7:20 AM
Subject: Re: [PCW] Power-Cats and the Volvo IPS or MerCruiser Zeus Drive
systems
DISCLAIMER: This letter written by a catamaran dealer.
Hello power-cat fans,
Here's a question (especially to the cat designers and builders who read
this site) regarding a pair of new propulsion systems. I'm wondering if
any of you know of any power cats that are offering (as standard or
optional equipment) either of the new "pod-drive" systems? That is,
either (a) the Volvo Penta IPS (Inboard Propulsion System), distinctive
for its forward-facing props, or (b) the Cummins MerCruiser Zeus Drive
(aft-facing props) system?
As a catamaran dealer, I've just happened upon the most clear-reading and
understandable article about these two systems that I've seen thus far.
The article, "The Pod-Drive Revolution" (by Chuck Husick) is in the newest
issue (Jan/Feb 2008) of "POWER CRUISING" magazine. The purported benefits
(lighter weight, less draft, no rudders, usually undetectable exhaust
fumes, quicker pick-up performance, no need for muffler, or water-intake
thru-hulls, 20% better fuel consumption, etc.) are, understandably,
appealing. But I'm wondering if there's anything about the catamaran
design that presents a possible drawback to this new propulsion system?
The fact that some major monohull yacht builders (Grand Banks' 41
Heritage, Legacy Yachts and Sabre Yachts) are now employing one or the
other of these 2 systems proves there's growing (and serious) support.
So, any cat lovers out there, designers/builders or not, who have any
first-hand feedback about either of these systems?
Thanks in advance,
Rod Gibbons
Cruising Cats USA
Seattle, Portland, Oakland, Hawaii
Power-Catamaran Mailing List
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12/26/2007 5:26 PM
Tim et al
The figures quoted are not really a fair comparisons for these engines.
The nomenclature for the Volvo Penta IPS drives represent the hp equivalents
of standard shaft drive installations therefore:-
The IPS 350 should be compared with a 350hp installation not a 260hp
Equally the IPS 600 should be compared with a 600hp setup not a 350hp
The Yanmar 6LYA-STP at 370hp weighs in (dry) at around 600kg
These comparisons together with the proven advantages of "pod drives" makes
them a better proposition than Tim's figures suggest.
Also these big engines would be fitted to big, planing cats and as such
represent a more acceptable proportion of the total mass of the vessel.
Yes?
No?
Regards
Roger Bingham
France
Rob,
We have looked at these motors and they certainly have many
advantages, except
one which is important to cats generally, weight distribution.
IPS 350 (260hp) weighs 790kg
Yanmar 6BY220Z (260hp) with gear 365kg
IPS 600 (435hp) weighs 910kg
Yanmar 6LY28STP (440hp) with gear weighs 558 kg
Times that by 2 motors and fitted onto the stern of the boat, equals
excessive.
Tim Jordaan
Noosa Cat here in Australia trialled a pair of Volvo IPS's on one of their
Power Cats about a year ago but I have not seen anything since. They claimed
increased performance and were generally positive about the trial. Not sure if
they're offering them as an option or not but I'm sure a call to them would
clear that up!
Cheers!
Lloyd
----- Original Message -----
From: rodgibbons@mindspring.com
To: power-catamaran@lists.samurai.com
Sent: Friday, December 28, 2007 4:20 PM
Subject: Re: [PCW] Power-Cats and the Volvo IPS or MerCruiser Zeus Drive
systems
DISCLAIMER: This letter written by a catamaran dealer.
Hello power-cat fans,
Here's a question (especially to the cat designers and builders who read
this site) regarding a pair of new propulsion systems. I'm wondering if any
of you know of any power cats that are offering (as standard or optional
equipment) either of the new "pod-drive" systems? That is, either (a) the
Volvo Penta IPS (Inboard Propulsion System), distinctive for its
forward-facing props, or (b) the Cummins MerCruiser Zeus Drive (aft-facing
props) system?
As a catamaran dealer, I've just happened upon the most clear-reading and
understandable article about these two systems that I've seen thus far. The
article, "The Pod-Drive Revolution" (by Chuck Husick) is in the newest issue
(Jan/Feb 2008) of "POWER CRUISING" magazine. The purported benefits (lighter
weight, less draft, no rudders, usually undetectable exhaust fumes, quicker
pick-up performance, no need for muffler, or water-intake thru-hulls, 20%
better fuel consumption, etc.) are, understandably, appealing. But I'm
wondering if there's anything about the catamaran design that presents a
possible drawback to this new propulsion system? The fact that some major
monohull yacht builders (Grand Banks' 41 Heritage, Legacy Yachts and Sabre
Yachts) are now employing one or the other of these 2 systems proves there's
growing (and serious) support.
So, any cat lovers out there, designers/builders or not, who have any
first-hand feedback about either of these systems?
Thanks in advance,
Rod Gibbons
Cruising Cats USA
Seattle, Portland, Oakland, Hawaii
Power-Catamaran Mailing List
Roger,
the specification of the IPS 350 has a crankshaft output of
260hp at 3.500rpm
the IPS 600 a crankshaft output of 435hp at 3500rpm, maybe there
are other
interpretations regarding HP.
Tim
----- Original Message -----
From: "Roger Bingham" rbingham@tele2.fr
To: "'Power Catamaran List'" power-catamaran@lists.samurai.com;
rodgibbons@mindspring.com
Sent: Friday, December 28, 2007 10:22 AM
Subject: Re: [PCW] Power-Cats and the Volvo IPS or MerCruiser Zeus Drive
systems
Tim et al
The figures quoted are not really a fair comparisons for these engines.
The nomenclature for the Volvo Penta IPS drives represent the hp
equivalents
of standard shaft drive installations therefore:-
The IPS 350 should be compared with a 350hp installation not a 260hp
Equally the IPS 600 should be compared with a 600hp setup not a 350hp
The Yanmar 6LYA-STP at 370hp weighs in (dry) at around 600kg
These comparisons together with the proven advantages of "pod drives"
makes
them a better proposition than Tim's figures suggest.
Also these big engines would be fitted to big, planing cats and as such
represent a more acceptable proportion of the total mass of the vessel.
Yes?
No?
Regards
Roger Bingham
France
Rob,
We have looked at these motors and they certainly have many
advantages, except
one which is important to cats generally, weight distribution.
IPS 350 (260hp) weighs 790kg
Yanmar 6BY220Z (260hp) with gear 365kg
IPS 600 (435hp) weighs 910kg
Yanmar 6LY28STP (440hp) with gear weighs 558 kg
Times that by 2 motors and fitted onto the stern of the boat, equals
excessive.
Tim Jordaan
Power-Catamaran Mailing List
--
No virus found in this incoming message.
Checked by AVG Free Edition.
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12/27/2007 1:34 PM
I appreciate what you are saying, Tim, but that the power output quoted
below are absolute terms.
What Volvo say is that because of the increased efficiency etc etc of the
IPS drive - their 260hp engine connected to an IPS drive equates to an
output of 350hp for an engine connected through a standard reduction gear.
Therefore a builder can use a lower rated IPS engine for the same/similar
performance envelope of a larger "standard" installation.
Their claim/explanation - not mine.
Regards
Roger Bingham
France
Roger,
the specification of the IPS 350 has a crankshaft output of
260hp at 3.500rpm
the IPS 600 a crankshaft output of 435hp at 3500rpm, maybe
there
are other
interpretations regarding HP.
Tim
I have a few questions on these drives too:
-
When you hit an object in the water, such as a log, what is the failure
mode of the IPS? -
Will the pod shear away before that very large thru-hull penetration
fails? -
If the IPS is seriously damaged, what is the replacement cost?
-
How much fuel can you purchase for the price of a replacement IPS pod?
Bob Deering
Juneau, Alaska