cruising costs, maintenance and price of the boat (sailboats versus motorboats)

Discussion in 'Boat Design' started by Vega, Apr 28, 2006.

  1. john.G
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    john.G Junior Member

    Interesting thread. and it's taken a damm long time to read it through.Can we throw this into it?

    I used to run a Tasmanian crayboat that had been converted across to a shark netter. 48' round bilge aft weelhouse, hull similar in shape to a north sea trawler. Operating area was the Coral Sea out to 200nm. She carried 4000litres of diesel for an operational range of 6000 nm. Main power was a 120 HP class A (heavy commercial) Gardiner. Speed 8 knots. Also had a mast and sails good for about 4.5 to5 knots (but keeps the insurance down)

    While I personally never seen worse then a good force 9 in her, she done it easy. They are renowned for their sea keeping abilities, and the next skipper went through a Cat 2 cyclone, although he swallowed the anchor after that trip.

    There are quite a number of boats of this type that have been converted across to pleasure usage around Australia. And while they might be ugly by production standards they do have a sort of charm about them. And you can buy a good second hand one for about 120k AUD. with current electronics and survey and watermaker already fitted. Figure on 40k AUD to convert the fishhold to liveaboard space.

    Fast passagemaker - NO. Cheap, safe passagemaker - YES.
     
  2. Guillermo
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    Guillermo Ingeniero Naval

    Nope. But, who cares...?
    What is happening is that all the discussion on economy and fuel efficiency seems to worry everybody but, at the end of the day, only a few really care....Most of the people go on buying boats being their priorities things like price (!), dreams (!), styling, proudness, biggest possible interior room & comfort, real time available to enjoy the boat, coast geography & local weather, skills, etc, etc. My feeling is that fuel efficiency only comes in a sixth or seventh place, at its best, for the huge majority. And seaworthiness also.
     
  3. Vega
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    Vega Senior Member

    Hello John,

    Certainly we can join your boat to the discussion, but I live on the other side of the planet and I don’t know what a Tasmanian crayboat is. I had a look at the net. Is it one of this kind ?

    As all seagoing professional small craft it means business, and professional oceangoing crafts will normally out perform pleasure crafts, regarding safety and seaworthiness.

    But if you compare the initial price of a professional boat with a pleasure one, the professional will be a lot more expensive.

    Of course if you can find one in the second hand market at that price, it will be an interesting choice, if you like it simple. Because if you really put an interior on that boat to match the quality of the living interior of a boat of that size, with all the amenities that come with it, you will spend 10 times more than the amount you have envisaged for it.

    What you have is a hull and an engine, and in a pleasure boat the interior costs 4 to 5 times the price of the hull, and comparing with that, the value of the engine is not so high.

    But of course, if what counts for you is cruising, and if you can pass without the commodities of a comfortable and luxurious interior, certainly it will be a good option.:)

    I have nothing against it. When I was younger, I have cruised extensively, I mean living aboard for about 45 days in a year, in a boat that was just a bare hull without any interior, nor electricity and practically without an engine, and I have lived there some of the happiest moments of my life.

    But, regarding this thread and the general market for motorboat cruising, I guess that we are talking here less of cruising extensively and more of living aboard. And normally people that can afford a cruising boat (unless they are rich) are no longer young and want a decent level of comfort while enjoying their holidays or retirement.;)
     

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  4. fcfc
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    fcfc Senior Member

    Who can cruise at 7 kts for 10 hours when the boat is capable of 21 kts ?:D
     
  5. Vega
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    Vega Senior Member

    fcfc, this time I completely agree with you.
    These are the kind of boats that motorcruisers want. That’s why all new produced boats (trawler like) have more or less similar (high) power requirements.

    Perhaps a small precision, those are not properly planing boats, but semi-planing boats.

    Yes, of course, and why cruise at 21kts if your boat is capable of 36 kts?
     
  6. Vega
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    Vega Senior Member


    It is not only Beneteau that think the same way. Almost all the market thinks the same way and that means that motorboat cruisers think that way, because they are the ones who make the market.;)

    And trawlers capable of crossing oceans are so rare that we can ignore that very small niche market. The big new “modern” trawlers with their huge engines would not have the autonomy for a crossing.

    And no, we don’t need a new thread, because this thread is about mass market boats, budget cruising market boat trends , sailboats and motorboats, and the comparative costs of those options.:)

    You don’t want to discuss very fast and wasteful cruiser motorboats but relatively economical motorboats that can cruise at a higher speed than a sailing boat, and that is what the market wants, even the ones that are really concerned with the fuel costs, the ones I call budget cruisers.

    I have to say that if I cruise in a motorboat I will not cruise at the speed of a sailboat. Motoring for 12, sometimes 24 hours at 6,5 knots is BORING.:p The fun part of a sailboat is when you sail, preferably with lots of wind. A motorboat without the fun of sailing and without the speed advantage is a very boring boat. But that is only my personal taste.

    So, when I have time I will see about costs of cruising in one of those new trawlers that fcfc had posted.;)

    I agree with Guillermo on this. A semi-displacement hull is not efficient at hull speeds and it is also less efficient at planing speeds than a really planing hull.:(

    The only type of boat that can do both things relatively well is the long and narrow hull (with little interior space), and not the trawler type( I am not talking of planing speeds, but of speeds between 15 and 18 kts).

    A 300hp engine will also not be efficient at low revs. A 100hp engine running at its optimal rpm will be a lot more efficient regarding fuel consumption.

    The economical difference in operating costs, between one of those relatively economical semi-displacement boats and a true efficient displacement hull has to do with the number of miles you cruise each year.

    If you cruise few miles, then a semi-displacement boat will be a better choice because it will have more value in the used boat market (almost nobody wants low power trawler motorboats). If you cruise a significant number of miles we will have to make some calculations to see what is the relevance of fuel costs (and maintenance of bigger engines) in the global costs.:cool:
     
  7. Vega
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    Vega Senior Member

    No Guillermo, nothing personal and you have not offended me. I was only pissed at your poor aim, regarding the subject of the thread. You are shooting a lot better now.:D

    “Quote: Originally Posted by Vikendios
    ..Can small (32 to 40 ft) trawlers with planing hulls and twin 200 / 300 HP engines also (emphasis on also) troll reasonably efficiently at hull speed when max fuel economy is wanted ? “


    I guess that you are right regarding most of the boat owners. Most of them hardly use their boats.

    But for the ones that make some thousand of miles/year, (and that are the ones that cruise), you can bet that for a cruiser motorboater, fuel consumption is not the sixth or seventh priority, but is between the 3 first ones. Of course you probably are right if we are talking of a rich man but this thread is not about those.

    Consumption of a 40/42ft cruising motorboats can vary between 0,6L/mile to 7L/mile.

    Giving my annual cruising mileage, that will give in fuel costs, for the first one, 1500 euros, for the second 17 500 euros.

    My complete cruising season for the four of us, including everything, cost me only a fraction of the cost of fuel wasted by the faster boat, and sometimes I think I am spending too much money cruising….:(

    By the way, what is your annual cruising mileage and where will you cruise this season?:)
     
  8. john.G
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    john.G Junior Member

    Vega,
    you are completely right about the costs of fittng out a hull as a percentage of the total. I was talking about 4 berths and a 15 cum beer fridge not a floating bordello:)

    But what I was getting at was the running costs. The answer to going further cheaper is not about increasing horsepower, it's about being able to swing a bigger prop. A slow reving marine diesel swinging a big prop is cheaper to run then an high HP automotive conversion that runs at 3000 rpm hooked up to a smaller prop that gives the same output in terms of thrust.

    It's a matter of initial outlay versus ongoing savings in terms of fuel and maintenance. For most private vessels, the cost of heavier shafts and bigger props is a one off, as it takes a long time to wear them out. And I think that as fuel costs continue to rise a segment of the market will realise this.

    Enjoying your debate.
     
  9. john.G
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    john.G Junior Member

    Vega,
    Picture of similar vessel currently for sale locally. This ones a 42 footer built 1988 (carvel hull) in current survey. asking price $85k AUD including fishing gear
     

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  10. fcfc
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    fcfc Senior Member

    The problem is not so clear:

    I once saw a technical/economical/marketing preliminary study (made by students/trainees, accounting and engeenering) for a small repair shipyard where the owner wanted to open a powerboat renting dept. The primary idea of the owner was : people rent sailboats, but some NEVER put sails on. Why not propose to theses customers slow powerboats at prices not too far sailboats rent prices. (A 33 ft planning powerboat is typically rented two to three time the price of a a 33 sailboat).

    The boat envisaged was somewhat a crossover with a GB32 look (very classical and looking safe), nimbus 320 layout (2 sleeping cabins with dbl berths) and Adria 1000 construction (money, money :D :D ).

    From memory, a part of the study was comparing a D2 75 with 1:2.6 gearbox , 1"1/4 (30mm) shaft and 22" prop, with a 2300 rpm saab/iveco engine, 1:4 gearbox, 2"1/4 (60 mm) shaft and 34" prop.

    For the props only, a 22" is in the 500€ range, a 34 is 2000€. (customer replacemet if damaged). Then the added draft. You need 20% clearance between hull and prop, and 10% between prop and skeg bottom. So draft increase is 12*1.3 = 15.6" (40 cm).
    Difference in price for shaft, stern tube, bearings, stuffing box, skeg (for the higher draft), rudder (higher in front of a bigger prop). It is just a matter of higher initial cost.
    Then for the engine. Difference in the engine price: not too much, but vibration/soudproofing a 1000 lbs engine at 2300 rpm is much more expensive than a 500 lbs 3000 rpm engine. This was magnified by the fact the D2 is turbo, so already has a dampening effect on intake/exhaust.
    And there is a big price difference in the gearboxes, which are sized to torque, not power. As I recall, the big gearbox was in the 3000€ range, the small in the 1000€ range.

    Then, the overall difference in ancillaries initial cost was around 7000€, for about similar power and engine price, but one prop at 1200 rpm, the other at 600 rpm. Perhaps in previous posts, I did not told the whole story. But this case is extreme since you even size skeg and rudder/rudder shaft according to prop diameter and have the same level of noise with either engine. Of course, bigger starting batteries and bottom engine stringers were taken in consideration for the heavy engine. At contrario, this means that the small engine ancillaries were sized at minimum for that engine.

    For the maintance cost, it was not a real problem in that context. You seldom rent more than 10 years old boats. Rent companies buy new, rent them 5 to 10 years, and sell the boat then. This is to avoid big maintenance costs.
    But the resale value is a concern. It was though that the resale value of the big stuff would not cover its initial price. A boat with ligth, but know D2 volvo and "inexpensive" equipment deprecates less (sells better) than a heavy, but marginal saab/iveco with "expensive" equipment around. The boat would be kind of a "noname" brand, since it would have been custom built for that application.

    For fuel, it was easy. It is the customer who pays the fuel bill. Not the rent company. It was just checked that in both cases, fuel bill would be small compared to a week rent price. Estimated 30 hours motoring in a week.

    Another part of this study was more marketing. The throttle lever of such a rent boat would be used at two positions only. idle and full throttle. The engine difference translated in speed, not fuel burn. The difference in speed was something between 8.5 kts at 17.5 l/h for the D2, and 9.3 kts at 16 l/h for the SAAB.( not sure for speeds ,remember one in the 8, the other in the 9, and diff less than, but near 1 kts). This was not juged relevant for any customer. What to say to customers if they want to save fuel : "slow down by one knot" and the boat, any engine, would be advertised as "7.5-8 kts cruise at 10 l/h. May vary with loading and weather conditions."

    The final of this study for this application was the D2 would be far more economical (real terms : would generate higher profits).

    And even for an individualy owned boat, you have to recover 8500€ (7000€ + sales taxes) in fuel costs. May be if you slow down to 8.5 kts, you would save 5l/h from the D2 engine. (a 30% saving) But at 1.2 € per liter, that's over 1400 hours or 12 000 nm. Nearly 5 years just to break even. And this only if the D2 engine owner chooses not slow down too.


    PS: The project collapsed because the company owner put his money in what he though safer investments.
     
  11. Vikendios
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    Vikendios Junior Member

    Cost of running planing hulls at hull speed, compared to displacement hulls.

    To answer my own questions, I have found that the power calculator featured in boatdiesel.com can be used. (Yes, I forked out the 25 bucks)

    Taking the NordHavn 40 as an example ( LWL 35.5 ft, weight 50000 lbs) it takes 100 hp to achieve its hull speed of 8 Kt. If the same boat had an 'average' planing hull, it would take 114 HP to achieve the same speed. The penalty is therefore 14 % in HP, which we can assume to translate linearly into Litres of fuel or cost.

    I believe a 14 % fuel cost penalty is not excessive.

    PS for Guillermo : I can afford a GB, but because I cruise for three months in any given year and am now switching to power, fuel costs is to me a huge concern.
     
  12. fcfc
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    fcfc Senior Member

    Beware of small calculators. By the way, what "average planning hull" weigths 50000 lbs for 35.5 lwl ? Are not you a bit out of range ?

    In the previous post, for the same displacement hull, same speed, fuel burn can vary about 30% by just varying the prop from 22" 1200 rpm to 34" 600 rpm, the reduction ration, and the engine operating point. This study was done with a professionnal package. (navcad I think). This give you an idea of the possible error range.

    And the third point : a planning hull with propulsion optimized for displacement speed and used at displacement speed is not the same as planning hull with propulsion optimized for top planning speed, but used at displacement speed. I do not think the calculator you used take this in account. It just assume that the propulsion you use has a "average/good" efficiency at the *single* speed you ask.

    You can have also "real" figures here : http://www.beneteaupower.com/swift/performance.php
    You can also have figures for a displacement hull http://www.kadeykrogen.com/39/index.php?page=performance_data
    Both about same size, same weigth. 39 ft, 30 - 33000 lbs.
    At 7 kts , the krogen 39 does 2620 nm. Corrected for tank capacities (both range = 90% tank) = 2620 * 395/700 = 1478 nm.
    At 6.4, the beneteau trawler is 718 nm. at 7.4 kts it is 572 nm. Averaged at 7 kts, should make about 630 nm.

    So the penalty is not 14%. It is 130%. One zero more.
     
  13. Vega
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    Vega Senior Member

    I have made those calculations and it seems to me that it is a lot worse than that, I mean regarding the mileage you have to do to compensate the difference in price between both engines. And that is consistent with the calculations I have made regarding the two types of engines on the sailboat/motorboat comparison (and it was you who has given me the data and information to work it out, thanks for that).

    Regarding those two engines and the consumption and speed numbers you have posted, the volvo will waste 2,06L/M and the Saab 1,72L/M. The difference per mile would be 0,34L/M. The mileage necessary to cover that difference would be 25 000 miles, or 2941 hours on the volvo engine (considering only fuel costs).

    (I am considering 1L=1euro)

    Considering fuel costs and also cost differences in maintenance between the two types of engines (including the superior working life of the Saab engine), it would be necessary to cover 19 875 miles (2338 hours) to recover the higher initial price of the Saab.

    Putting it in a simpler way. If you are going to do a lot less than 2338 hours with your boat (during all time you own it), you would lose money, but if are going to end up doing 15 000 hours in your engine (140 000m), then you would save 54 533 euros.

    Regarding the dilemma, I will say that if you are a cruiser, even if you only make 10 000 miles before selling your motorboat it still remains a god deal. You would lose about 4000 euros, but that is probably meaningless compared with the value of the boat, but you have owned a safer boat (superior reliability of the Saab engine) and have had a lot less maintenance services and that means, less ******** and more time cruising.

    If you are not a cruiser, go with the volvo. Regarding the charter business, it is not worth it.
     
  14. Vega
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    Vega Senior Member


    fcfc has said it all, even if I don’t know if those 130% are for real. I believe that you have to study each case.

    But regarding the example you give, a Nordhavn 40 and a GB 44 weigh about the same, and the GB, due to his much bigger waterline, will plane with less power than the Nordhavn. That boat is a semi-displacement trawler and it comes with two engines of 567hp, for a max speed of 25 kt and probably a cruising speed of about 18 knots. The Nordhavn, with an adequate hull would need at least the same power.

    If you put one of those big engines pulling the Nordhavn at hull speed, how much more fuel would you be wasting, comparing with the 105 hp original engine?
     

  15. Vikendios
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    Vikendios Junior Member

    Trolling with trawlers (contd..)

    To Fcfc :

    I made the calculations again using the data on the GB 44 (non-Acert C5 at 505 Hp) and the near identical Kroger 44, and the results at 7.4 Kt is 1.8 M/g for the GB, and 3.4 M/g for the Krogen. Vous avez raison, mon cher, and I stand corrected.

    But I still think this is quite an interesting and useful way of cruising for some longer legs on a GB 44.

    Cordially,

    Vikendios
     
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