Semi displacement / planing, fuel prices

[henryf]

As soon to be boat less boaters we are in the middle of sourcing our next vessel. The Princess 42 has a been a dream. Around a mile per gallon is something we can and have lived with without too much trouble. We fill up every now and again in normal cruising, on an extended cruise such as our trip to the West country last year we fill up more regularly but it's a holiday and so we accept it.

The move up to a larger, circa 50 foot flybridge will, from what I've read, mean circa 0.75 miles per gallon. That coupled with all the doom and gloom on here about the prospect of fuel costing more than fine brandy in a few years made me take stock and have a little look around as to other possibilities to the assumed flybridge purchase. I fell in love with the Elling E4. I saw one some years back in Swanwick and thought it was gorgeous and I quite like the thought of an ocean cat A self righting craft. I haven't been to see one in the flesh so my comments are purely hypothetical. I've read all the articles, seen a few videos and spoken briefly to the factory.

However. To get good fuel efficiency from something like the E4 means circa 7.5-8 knot cruising. If need be it will cruise at circa 16 knots returning the same sort of fuel efficiency as our current Princess 42, around a mile per gallon. But realistically how often are we going to cruise at 7.5 knots? A trip across Lyme Bay goes from 3 hours to 10 and Cowes (from Portsmouth) is getting on for an hour and a half rather than 20-25 minutes.

Like most people I still have to work for a living so I'm cash rich and time poor. Being able to turn up on a Friday nit and have dinner in Cowes means an extra nights holiday rather than sitting in the marina and the sums get even more extreme if we decide to take a run down to Lymington, Yarmouth, Poole or beyond.

The worry in the back of my mind though is resale. When it comes time to get shot of a larger flybridge will it be a historic curiosity in a a sea of displacement / semi displacement craft?

So I crunched some numbers to try and put things into perspective. Keep in mind that we are talking new / nearly new in terms of boats. I'm not running a sub £100k older boat.

Our P42 did around 250 hours in 4 and a half years. I'm actually going to up that a bit and call it 70 hours a year. I'm also going to ignore the fact that 70 hours doesn't mean 70 hours at full chat doing 24 knots (a gallon a mile). In reality I bet that's circa 50 hours of actual cruising.

A quick peek at the Cowes Harbour fuel website shows commercial diesel at £0.83, 60/40 at £1.13 and petrol (so presumably diesel with all the concessions removed) at £1.49. They also list a discount of £0.02 at 500 litres, £0.03 at 1,000 litres. So around £8,316 using 60/40 £11,265 assuming £1.49 a litre.

A 50 footer is going to be around 1/3 more.

So for the relatively few times when I will actually cruise at 7.5 knots does displacement / semi displacement really make that much of a difference?

I see a lot of Nordhavens sitting around in marinas and I see quite a few relatively new ones for sale in the world. 1 suggestion is that people have been caught out in bad weather (because they can't outrun the storm), the family get spooked and the boat goes up for sale. A boat might take the pounding, the fair weather crew might not.

Sorry if the above all seems a bit of a ramble, I'm just trying to get my head around the whole doom and gloom of the forum at the moment in the context of buying a 50 foot boat.

Henry

 

[benjenbav]

I have a (smaller) semi-d vessel. It's much more efficient at 1,400 rpm/7 knots but I don't have the patience so I tend to cruise at 2,000/12 knots...unless I am in a hurry.

PS I chanced to be reading an old MBY yesterday which had a feature about Elling E4's crossing the Atlantic. If you haven't seen it and want to, let me know and I will happily look the article up for you.

 

[gjgm]

What is the consumption of 50fter at 8 knots?
With the planing boat you have choice to slow down I guess, but you dont have the choice of doing 25 knots in the E4...

 

[Firefly625]

Henry

There was a forumite with an Elling on the Solent... he had been trying to sell it...

Your comment of Nordhavn crews getting spooked by bad weather reminded me of this video I saw....so not sure about your theory, along with their boats the crews may just continue as if it was just another day..?

 

[Trundlebug]

I have a displacement boat and 7kn is what I have to plan for and live with.

I think if (or when) we ever come to sell it'll be worth quite a bit more than we paid, although much of this will probably reflect all the improvements I've done as much as the fuel price changes. It's a much older boat than you're looking at though (1988).

In summary, we don't have a choice, 7kn is the boat's capability and that's it. (4mpg is nice for a boat though).

With a faster boat, you can choose to go fast and blow the consumption if your time is more important or a storm is catching you.
If you choose to go slower because the weather is fine and you want to save fuel, then you can. You have more options - but only you know your cruising circumstances and willpower. I can understand it would be like driving an S class at 29mph everywhere. (Although there seem to be plenty that do, quite unashamedly!!) But at least you wouldn't be getting in everyone else's way!

 

[Robin]

We are newbies to mobos after in my case 50 years of sail and SWMBO 24 years of it, but our new boat is a 47ft semi-displacement so called 'fast trawler' yacht in the USA. We did a lot of research before buying and came to the conclusion that outrunning any storm is wishful thinking and the best you could say would be that you could use a smaller weather window, if you trusted the forecasts enough. We will be running our new boat at around 8kts, which is fast compared even to our 41ft cruiser racer under sail! The thing is whilst we can do 17kts WOT we will run at 8kts and average 8kts, whilst before under sail we could be doing 8.5/9kts even surfing over 10kts but the average would still be nearer 7.7kts, that is the reality. I'm looking at speeds over a displacement speed of 8.5kts as being there just for very short term use, like what they call in the USA 'running an inlet' from the ocean into the ICW when the having the speed to stay on one wave is very helpful.

Been on several Nordhavens and they really are very nice indeed if you have the money and of course if you don't mind the displacement speeds.

We also looked at the Ellings in the UK and they too are very nice, although (and remember without experience of mobos) we favoured having a flybridge as well.

 

[PaulGooch]

Henry

There was a forumite with an Elling on the Solent... he had been trying to sell it...

Your comment of Nordhavn crews getting spooked by bad weather reminded me of this video I saw....so not sure about your theory, along with their boats the crews may just continue as if it was just another day..?

Our grandkids love a bit of weather. When we turn around and head for shelter because it's getting rough, they are most upset lol

 

[henryf]

Bloody hell. The kids in that video would make me consider taking to the tender and chancing it with a run to the shore

I've read some of JFM's posts when he talks of throttling back to 6 or 7 knots and pottering along if the weather is fine. I've never done that on our boat but I suppose there is nothing to stop us and we too would enjoy multiple mile per gallon fuel efficiency. I understand a planing hull will roll more in sea so you'd only do this in flat conditions but to be fair I'm not sure if my lot would be happy punching through big seas for several hours in a semi displacement boat. They would rather we out ran the storm.

The one thing I can't comment on is any improvement in ride quality during normal operation by going Semi-d. To be fair I would expect a 50 footer at circa 24 tonnes to show some improvement over a 14 tonne 42 (well actually 45) footer. I've never actually been out in a Princess 50. I did notice a difference just from things like the generator and pumps when looking at one with a view to purchase a couple of weeks ago.

I haven't seen an E4 for sale locally so I suspect either sold or withdrawn from sale.

With full displacement hulls you haven't got an option but I wonder how many semi d's are actually run at true efficient speeds against those run at higher speeds with owners kidding themselves that they are only using a thimble full every week and a half?

Henry

Henry

 

[henryf]

We also looked at the Ellings in the UK and they too are very nice, although (and remember without experience of mobos) we favoured having a flybridge as well.

Do you know the thing I like most about the flybridge is the roof it creates over the cockpit

I am happiest helming from down below, probably helped by unusually good visibility on the Princess 42. There are times when lounging on a bean bag up there is great but it's e cockpit roof which swings it for me.

Henry

 

[Robin]

Do you know the thing I like most about the flybridge is the roof it creates over the cockpit

I am happiest helming from down below, probably helped by unusually good visibility on the Princess 42. There are times when lounging on a bean bag up there is great but it's e cockpit roof which swings it for me.

Henry

We too have a roof over our 'sundeck' from the flybridge but we also have a hardtop bimini roof over the flybridge which can then be fully enclosed with clear roll up screens as well. With the down below helm position also that is spoiled for choice, but we are reliably informed by those in the USA we will always choose to steer from up top.

 

[LittleShip]

With full displacement hulls you haven't got an option but I wonder how many semi d's are actually run at true efficient speeds against those run at higher speeds with owners kidding themselves that they are only using a thimble full every week and a half?

Henry

The downside of Displacement......... but then again I dont think a planning boat would slam through this lot.

(Click below)



Knives and forks make a noise eh!

Man up ! it's still good fun

Tom

PS I was on my own out there ?

 

[henryf]

A P50 it is then

Henry

Edited to say:

Looking at the sea I think we would have just trimmed the nose down and used the stability at planing speeds to smooth things out.

A semi displacement boat such as the E4 could be run at 16 knots to get stability from the stern. The downside of course is that by doing that you're negating the whole fuel saving reason for going down the semi-d route in the first place.

H.

 

[kid's inheritance]

another reason for a planing boat is you can travel in a group without holding the rest back.
Rob

 

[Nick_H]

A P50 it is then

Henry

Edited to say:

Looking at the sea I think we would have just trimmed the nose down and used the stability at planing speeds to smooth things out.

A semi displacement boat such as the E4 could be run at 16 knots to get stability from the stern. The downside of course is that by doing that you're negating the whole fuel saving reason for going down the semi-d route in the first place.

H.

I wouldn't have a displacement boat at sea without some form of stabilisers. Most roll every bit as much as a planing boat, and it doesn't need to be a big sea, even a small swell on the beam will make them roll. A guy on our pontoon in Berthon bought a shiny new Linssen, about 43 feet, used it once and immediately chopped it in for another with stabilisers.

Personally if I wanted to go that slowly i'd buy a sailing boat, then you really save on fuel costs, and you have the keel and sail to stabilise it

 

[Firefly625]

........... A guy on our pontoon in Berthon bought a shiny new Linssen, about 43 feet, used it once and immediately chopped it in for another with stabilisers.

ouch

 

[Deleted User YDKXO]

You've already answered the question yourself. At the moment, you are cash rich/time poor and pottering about at 8kts is not going to suit your lifestyle and nor I suspect will it suit your family who will v quickly get bored if it takes you 1.5hrs to get to Cowes. For the kind of boating you do at present which I'm guessing is weekend jaunts and the odd foray across the Channel when you've got a spare day, a 20kt planing boat makes far more sense.
I am in the same situation as you at the moment which is why I keep a 53ft planing boat but I happen to be looking at d/semi-d boats at the moment because I'm planning for my lifestyle to change in 2/3yrs time from being cash rich/time poor to being cash rich/time rich, although the way that our various pension funds are performing, its more likely to be cash poor/time rich If/when that happens, we will have a lot more time to go boating and a lot more inclination to go much further afield and, in that case, we will need to have a boat that is more economical and has a more extended range which means a boat that performs well at d speeds.
Now we come to the slightly thorny issue of whether a planing boat can be used extensively at d speeds. No question that something like a Squadron 50 is going to be more economical at 8kts than a Nordhavn 50 but thats almost entirely down to the fact that the Nordhavn is built like a brick sh**house and weighs about twice as much as the Sq50 and the same goes for other d type and semi d type boats compared to planing boats. Planing boats are built for lightness and speed whereas d boats are built for strength, comfort at sea and fuel capacity. On the subject of fuel capacity, that is another big difference between planing boats and d/semi d boats. A Sq50 carries 500gals whereas a typical 50ft d or semi d boat might carry nearly twice that amount or a lot more and that is worth having, not only for range but for the ability to buy fuel in the cheaper places. Personally, I think planing boats are less suited to extended passages at d speeds for other reasons as well such as lack of proper seagoing galley, lack of separate pilot house, lack of internal steps to f/b, lack of handholds, lack of proper helm seats and a whole host of other things which make life easier at sea. Then there is the engineering. I'm not in any way knocking Fairline which represents the best of its type but the engineering is not on a par with the bombproof engineering you see in something like a Nordhavn or Fleming for example. Neither do you tend to get equipment like fuel polishing systems, oil change systems, double fuel filters, hydraulic thrusters, double gensets etc etc. As for stabilizers, I don't think thats an issue these days as stabilizers can be successfully fitted to planing boats as other forumites have proved.
Having said that, you're right, you do quite often see bluewater cruisers like Nordhavns sitting around in marinas but I guess many of those belong to owners who have been seduced by the rufty tufty image but in fact, who's lifestyle is more suited to a planing boat. IMHO this is where semi d boats come in which to some extent offer the best of both worlds or the worst depending on your point of view. Certainly, the likes of Flemings, Aquastars, Outer Reefs (that's for you, nautical!) do make good d boats when fitted with stabilizers and have most if not all of the characteristics I've listed above and they can pick up their skirts and plane at 14-17kts if you want although with much higher fuel consumption than similar planing boats. However, a semi d boat is still designed to plane and will not have the deep ballasted hull nor the fuel capacity of a Nordhavn but it's a compromise that is acceptable to some boaters.
To sum up, I would say that if your cash rich/time poor lifestyle leaves you limited time to go boating, stay with a planing boat but if you find yourself with more time and an inclination to go further, then probably a d or semi d boat is a better choice

 

[jfm]

Henry I think you're thinking too hard about it and worrying about the fuel money way too much. In a bit more detail:

1. Just buy the boat you like. No-one buys a Porsche because of just technical stuff. They fancy the car and then just sometimes quote the technical stuff to justify the purchase. If I came to your showroom you could tell me zillions of logical and other reasons why I should buy a Porsche and which model, but whether or not I do will just be down to my gut feel of whether I fancy it, whatever reason I own up to. So if a Prin 50 is what you fancy, buy that!
2. Dont worry about the price of diesel. It will go up, but not to a level where the richest 20% or whatever % can't afford it. The price is based on supply-demand plus tax, and both those factors contain some natural checks and balances and remeber that one cannibalises the other economically. Macro economicwise, everything on this planet has to be affordable Henry. Everything on it has to belong to someone and be capable of being bought by someone else, so all the oil that squirts out of the ground has to be priced at a level where enough people buy it. The thing that could change prices would be big contraction in supply, but that is decades and decades away
3. You're being too logical with this D thing and you'll hate it. As someone above said, it's nice to be able to choose whether 7kts or 23
4. I have done some slow crusing last summer with nice flat stabilised ride and 4x better mpg or whatever, but in truth it has been about 15% of my cruising miles only. Only 3 weekends ago I made a nice trip and never went above 8 kts. I have to be in the mood for it, and would hate it if I had no choice. I'm going to work myself up to 25% then 35%, but it'll be choice so I wont resent it.
5. I dont want to start a big OT debate with D-Lovers but I personally think the ride comfort of a pure D or SD, compared to a P, is pretty much the same. Hull shape isn't THAT important to ride AOTBE. If I gbround of the chines from your p42 and rounded the stern to get rid of the flat trnasom, AOTBE, you'd hardly notice ride-wise. Don't let alleged "pure D hull ness" make you get a boat that you don't love
6. Purely imho, there's no way a prin50 will be a white elephant due to fuel pricing in say 4-10 years when you might choose to sell it. When i started diesel non-dayboat boating, in a phantom 42 like your old one, 1999, fuel was cheap as chips. Red was under 20p/litre I think. It's now say 8x that but I don't see all these white elephant boats. Builders can't make enough 50 footers and larger. Sure, our personal incomes have risen a bit to keep up, but you can factor that into your planning to justify things too .
7. Completely agree with you about lid-over-aft-cockpit feature of f/b boats

Princess 50 or similar would be a fab choice and you'd be pleased as punch sitting on it saying quietly "cor blimey" to yourself.

 

[jfm]

Neither do you tend to get equipment like fuel polishing systems, oil change systems, double fuel filters, hydraulic thrusters, double gensets etc etc.

Actually you do. For the same weight/cost of boat you can get all this in PrinFairSeekerFerretti if you want. Most of that list is standard, the rest = ready-to-fit option.

 

[Deleted User YDKXO]

Actually you do. For the same weight/cost of boat you can get all this in PrinFairSeekerFerretti if you want. Most of that list is standard, the rest = ready-to-fit option.

Which of those items is standard on a Sq50?

 

[MapisM]

Which of those items is standard on a Sq50?

At a guess, I'd say the double fuel filters - if that.
But tbh, I wouldn't want to pay for any of the other equipment you mentioned, if I'd be interested in a planing 50' footer.
I don't really see the point of those, for a boat essentially aimed at coastal day cruising in fair weather.