Newbie question: sunseeker manhattan 50 - long distance trip.

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mcaquestion

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I have an opportunity to crew on a 600-650 mile delivery. I have zero motorboat experience - more of a raggy type. Looking for some elementary info.

From what I read the 50 seem to have 2500 litres fuel and twin 715hp volvos. What kind of strategy would be likely on 600+ mile delivery trip in the med? If you run the motors at 1000-1100 rpm, I suspect you might just about make it without refueling. (I looked up the fuel curve). However, I suppose you wouldn't want the tanks to get that low. If this a likely kind of strategy? How comfortable/uncomfortable would it be in 1m-3m seas? Advertising vids always show powerboats planing across duckpond calm seas.

Do many folks run that distance at 20+ knots and refuel x2 en-route?
 
mcaquestion said:
I have an opportunity to crew on a 600-650 mile delivery. I have zero motorboat experience - more of a raggy type. Looking for some elementary info.

From what I read the 50 seem to have 2500 litres fuel and twin 715hp volvos. What kind of strategy would be likely on 600+ mile delivery trip in the med? If you run the motors at 1000-1100 rpm, I suspect you might just about make it without refueling. (I looked up the fuel curve). However, I suppose you wouldn't want the tanks to get that low. If this a likely kind of strategy? How comfortable/uncomfortable would it be in 1m-3m seas? Advertising vids always show powerboats planing across duckpond calm seas.

Do many folks run that distance at 20+ knots and refuel x2 en-route?
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Fuel strategy depends on personal choices plus your route- open water or hugging coast. Plenty of folks would x2 refuel; plenty would go slow. Remember when going slow that 50 feet won't have much w/line length and even 10 knots will be pushing the bow wave, starting to plane and burning fuel. You would want about 8 knots or less for uber low litres per mile. You might find that boring- 75 hours so nearly a week.
It is possible to add a Volvo screen to the D12 715 hp to show real time fuel burn from the ECUs. I had that on those engines a decade ago.
 
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I did Naples - Cannes via Elba / Corsica in two running days @ 26/27 knots @ 180L /hr - same size engines as the D12 .
We topped up in Roma , Punta alla ( mainland near Elba ) and Corsica- arriving 1/2 full in Cannes about the same capacity as you .
Displacement speed 825 rpm burns 40 L / hr @ 9 knots - just too long .
The comfort is better planing in 1-3 M seas .
You need to move with the weather and sea state , if it’s beam or behind then plane otherwise 10 hrs for a 100 miles is just gonna wear you out rolling about.
Planing boats are just much more stable when up and off in most points to the waves ,with depending of hull shape the V profile , some are better than others in head seas .
Some pound or slam easier / sooner necessitating the helm to back off , others slice strsight through :)

Aim for 300 miles / day - done in 2 1/2 running and if you plan a week there could be be rest days weather wise anyhow .
Afraid the owner ( if it’s not been done allready) should have factored in the fuel costs in .

Wind and weather unlikely to stay the same over 6 days @ 9 knots over 600 miles in the Med .
If favourable then gun it !
ie if “ brochure “ pics mill pond then go as far as fast in a day .
 
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I'm with both above, it will be a fair amount of time doing nothing. Totally dependant on weather and won't be fun if that is against you.

We have done Mahon to Cyprus previously on a friends boat.

Flat out 30knts+ will probably be out of the question, fuel burn would be in the region of 300ltrs/hr combined, cut back to 18 or 20 knts and you can take >1/3 off that, probably something around 90per engine/hr ? That can offer a reasonable rate of progress, reasonable comfort and not crippling consumption. As JFM says get down to 8knts and from my experience with our D12s you could be in the region of 40ltrs/hr combined but that'll be a huge timescale for that journey.

Chances are you'll get a night crossing (that will be slower) on one leg which we thought was just totally fabulous, the night views are beautiful and totally humbling. and being out in open water for a sunrise was just breath-taking.

So yes, my experience is that a reasonable speed and 2 refuels is a reasonable compromise on that sort of trip.
 
Andrew M said:
Flat out 30knts+ will probably be out of the question, fuel burn would be in the region of 300ltrs/hr combined, cut back to 18 or 20 knts and you can take >1/3 off that, probably something around 90per engine/hr ?
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As those figures show, litres per mile ( which is what matters, not litres per hour) doesn't change a lot once you're planing. There is typically only say 15% difference in lpm between 19 and 27 knots. The choice is really to plane or to do 8knots, with not much in between. If you have decided to plane then choose speed based on comfort/sea/personal preference more than fuel economy.

As a separate point, it pays dividends to clean the hull and props before a trip like this. Lift the boat for a jet wash in slings just before you set off.
 
Thanks folks. A complete education about motor boating in four answers. The lpm point when planing is very good to know. I did see a post a few weeks back when looking up something else which mentioned that a clean hull makes a massive difference to fuel economy (range). I suspect the boat will be pretty clean as this is its second distance trip in a couple of weeks. I love night sails too - except for fishing boats which I find totally unpredictable.
 
The only way you can do 8 kts or whatever is with (a) a patient crew - I manage 30 mins some days - it is lovely but by then i cant stand any more and much the levers forward and (b) more importantly in a flat sea or it will pitch and roll like a pig and be very unpleasant.

You mentioned 1-3 m seas. Bear in mind planning hulls are not really meant for big seas ( generally for the leisure boater). In a 50 foot boat anything much above 1m is going to get quite uncomfortable unless you are going with the wind and waves of course. Personally I would say 1.5m is the limit for "normal" cruising. 3m waves ( unless with them) will be very hard work.

Remember also that fuel consumption varies dramatically ( as in +30-50%) in weather. I have real time fule monitoring and it is an eye opener when the boat starts to work hard going up waves and so on.

The litres per NM for most planning boats is relatively flat from say 15 knots to 200 rpm below max revs - so on a long trip you would want to press on as fast as the sea will allow.

Where are you going. Someone on here will have done it before.

Finally at the risk of the bleeding obvious do take fuel filters and have a personal EPIRB handy if you are going way off shore. They are only £150 and I have one to hand when i am going a long long way. Sardinia to Menorca by example is 200 miles and you see very few boats!

Finally Finally - get on board first and grab the mid cabin!
 
jrudge said:
The only way you can do 8 kts or whatever is with (a) a patient crew - I manage 30 mins some days - it is lovely but by then i cant stand any more and much the levers forward and (b) more importantly in a flat sea or it will pitch and roll like a pig and be very unpleasant.

You mentioned 1-3 m seas. Bear in mind planning hulls are not really meant for big seas ( generally for the leisure boater). In a 50 foot boat anything much above 1m is going to get quite uncomfortable unless you are going with the wind and waves of course. Personally I would say 1.5m is the limit for "normal" cruising. 3m waves ( unless with them) will be very hard work.

Remember also that fuel consumption varies dramatically ( as in +30-50%) in weather. I have real time fule monitoring and it is an eye opener when the boat starts to work hard going up waves and so on.

The litres per NM for most planning boats is relatively flat from say 15 knots to 200 rpm below max revs - so on a long trip you would want to press on as fast as the sea will allow.

Where are you going. Someone on here will have done it before.

Finally at the risk of the bleeding obvious do take fuel filters and have a personal EPIRB handy if you are going way off shore. They are only £150 and I have one to hand when i am going a long long way. Sardinia to Menorca by example is 200 miles and you see very few boats!

Finally Finally - get on board first and grab the mid cabin!
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Where do you get epirbs for £150 J?
 
As ( clearly!) I don't really differentiate between the 2 I think the key difference is that the EPIRB is (a) automatic and (b) floats and looks after itself.

The PLB has to be activated and held up etc to transmit.

The effect after that is the same and hopefully you all get a free helicopter ride.

For a journey in bad weather with the risk of immediate sinking then they would not be suitable. I have convinced myself that in the med I am more likely to have a mechanical / medical issue or somehow sink slowly whilst we all gracefully decant into the Williams and life raft!
 
mcaquestion said:
From what I read the 50 seem to have 2500 litres fuel and twin 715hp volvos. What kind of strategy would be likely on 600+ mile delivery trip in the med? If you run the motors at 1000-1100 rpm,
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At that kind of rpm, youre likely to be doing around 10-11kts and consuming 50lph of fuel which will only give you a 500nm range with 10% reserve. In a 50 footer you are very much pushing the bow wave at that speed and you'd be far better advised to drop down to below hull speed at around 8kts at which speed youre likely to be consuming 15-20lph which should give you around a 900nm safe range

Having said this, if this is a commercial delivery, time is money and the delivery skipper won't be interested in saving fuel for the owner so it is far more likely to be pedal to the metal at around 25kts and a route which has 1 or 2 fuel stops
 
petem said:
Not sure if anyone has made this point but the extra engine hours accrued from pootling may diminish any fuel savings.
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Actually I've made that point before on the forum and until buyers start assessing boats on total fuel burnt rather than engine hours it is going to be an issue. When I look at a boat to buy I try to check the total mileage (usually shown on the speed log) as well as the hours to calculate the average speed. If you find a boat that has done 500hrs and 15000nm, run a mile:eek:
 
Deleted User said:
Actually I've made that point before on the forum and until buyers start assessing boats on total fuel burnt rather than engine hours it is going to be an issue. When I look at a boat to buy I try to check the total mileage (usually shown on the speed log) as well as the hours to calculate the average speed. If you find a boat that has done 500hrs and 15000nm, run a mile:eek:
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very good points but does not help the op
 
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