S28 cruising RPM on KAD32's?

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S28 cruising RPM on KAD32\'s?

Hi guys,
As the title asks really, can I ask an S28 owner at what RPM's they cruise at with the 2 x KAD32 setup? And what speed this is at?

I want do come up with realistic costs of running as i'd like to have an S28 for next season yipee! /forums/images/graemlins/smile.gif Many thanks

 

[[2068]]

Re: S28 cruising RPM on KAD32\'s?

Anywhere between 2700rpm and 3300rpm, which is something like 17-24 kts.

dv.

 

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Re: S28 cruising RPM on KAD32\'s?

So I can expect almost exactly double the consumption than my single engined S23 KAD32, as I run around 3200-3500rpm cruising.

Cheers /forums/images/graemlins/smile.gif

 

[[2068]]

Re: S28 cruising RPM on KAD32\'s?

I would say a bit less than double.

S28 is running slightly coarser pitched props, hence not quite so many revs needed to get to the same speed. You might find that you're happy with 3000-3200rpm as a cruise speed.

KAD32 fuel usage is pretty much a straight line until 3000rpm (i.e. not much point going less than 3000rpm to save fuel), then increases after that.

dv.

 

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Re: S28 cruising RPM on KAD32\'s?

At a 3k cruise, would you find yourself using the tabs to keep the bow down?

 

[Overdraught]

Re: S28 cruising RPM on KAD32\'s?

I have Kad 32's in a Targa 30. Generally cruise at 3000rpm, giving c.23-25 knots SOG. Wouldn't normally go above 3200 rpm as a cruise speed, but as already suggested dropping below 3000 doesn't help fuel economy. I get around 2.5 mpg but suspect I'm a little heavier than an S28?

 

[[2068]]

Re: S28 cruising RPM on KAD32\'s?

[ QUOTE ]
At a 3k cruise, would you find yourself using the tabs to keep the bow down?

[/ QUOTE ]

Nope. Maybe a bit if running slower, say 2700rpm because it was choppy.

dv.

 

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Re: S28 cruising RPM on KAD32\'s?

That's great, thanks for the info guys

 

[Peanuts]

Re: S28 cruising RPM on KAD32\'s?

I like to run at 3300RPM, at this speed I find that the engines are running perfectly, of course allowing for the right conditions. 3000RPM is OK but the boat doesn't feel as lively as 3300, saying that with a slight chop/tidal etc you can carry on all day at that speed.
Regarding the MPG I tend to get slightly better then S28 does on his but I put that down to being at Poole and plodding through the harbour (only in the summer-speed limit lifted in winter) probably boosts the MPG.
For the trim tabs I run with 3 leds lit, this puts them level with the bottom of the boat, I checked this when the boat was out of the water, so if I move them from that position the boat reacts straight away.
I hope this helps and I bet you can't wait to get your S28!!

Steve

 

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Re: S28 cruising RPM on KAD32\'s?

Hi Steve,
Thanks for the detailed reply. \currently have an S23 and to be honest would be happy with her if I never sold and kept forever, however the wallet is allowing an upgrade, so why not? My main reason for gearing towards the S28 is simply because i'm dead impressed with the build of the S23 and I like it's practical use of space

So if I can sell the S23, an S28 will be on the cards ASAP, but if not i'll continue to bop around in my S23... win win situation /forums/images/graemlins/wink.gif

 

[poltergeist]

Re: S28 cruising RPM on KAD32\'s?

Having owned our S28 for less than two weeks now, we are totally blown away with it. Out in the Solent last Sunday, cruising towards Hurst, I opened the taps, and couldnt believe the acceleration of the thing - she absolutely flew when I increased from 3000rpm.

Only downside was watching the fuel guage go into free-fall !!! Doh

Alt, one thing I will say, is that the S28 feels a far more stable unit then the S23, of which I was initially in the market for. I thought the 23 was a cracking boat, and had real hardship trying to weigh up whether the 28 was a justifiable proporsition from a upkeep/ fun for the pound point of view.

I know we have made the right decision!

 

[[2068]]

Re: S28 cruising RPM on KAD32\'s?

At full chat, you can probably watch the fuel gauge move, but they do shift quite nicely with the KAD32's.

I've surprised a couple of ribs in the past
/forums/images/graemlins/cool.gif

 

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Re: S28 cruising RPM on KAD32\'s?

My main concern is that a usual weekend away for me consists of about a 60 mile trip, usually all of it on the plane. It's completely affordable in the S23 and I don't even need to think about the fuel consumption. My only concern is that this could change with the S28. I want to boat for fun, not to be constantly looking at the fuel gauge. My 'happy cruise' speed would be 25knots, usually in calm water

 

[[2068]]

Re: S28 cruising RPM on KAD32\'s?

Fuel consumption at 25kts shouldn't be too bad. It's when you put the "pedal to the metal" > 30kts that it all gets a bit scary (in terms of fuel).

dv.

 

[Whitelighter]

Re: S28 cruising RPM on KAD32\'s?

I guess you are using +-32l/hr in the S24 at 25knts. I From what S28 users are saying (and it looks about right) you would expect to use around +-45l/hr in the S28 for the same speed.

In money terms its going to cost you an extra £10 per hour to run the S28. Or in terms of your 60 mile trip, about another £25.

 

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Re: S28 cruising RPM on KAD32\'s?

I'm in Ireland jez, running the dirty green stuff /forums/images/graemlins/wink.gif Thank's for the comparison, an S28 is definately on the cards I reckon - here's to a good season next year!