Statement of Requirements – Foveaux Strait Commuter

Discussion in 'Boat Design' started by FoveauxSailor, Sep 4, 2015.

  1. PAR
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    PAR Yacht Designer/Builder

    I have a fair bit of time on a couple different size Bartenders and they're not as narrow bottomed as you might think. The entry is fine and the warp is farther aft than typical, but the WL beam was dragged back as much as possible, before it tucks into the stern post.

    The reason I think it's well suited is even in rough conditions, you'll be doing well over displacement speeds (mid teens), which will suit deteriorating conditions, yet still offer a good turn of speed to keep up steerage and get you home quicker and more comfortably. Running is rough conditions is more about skipper skill than hull form, assuming the form selected is capable. Being able to stay on top (with moderate speed) and not at the mercy of the sea can be key.

    If you want something more sure footed, I have a small power cruiser that will easily handle your conditions, but displacements speeds aren't what she's good at. Several are used offshore and it can take a beating and is a good stable fishing platform, but again, the wise skipper throttles down for the conditions, particularly inlets, where riding the back of a swell or breaker is the difference between getting in or having to wait it out.

    I don't think displacement or semi plane are a good choice, but I do think you need a design that has a wide range of comfortable operation, so you don't have to make a career out of a short passage. In this vein, I disagree (again) with Tom and do think one of his BlueJackets might be ideal. They can hold onto plane at lower speeds that typical and when it's nice, they can pick up their skirt. Tom would know more about his design's rough conditions abilities, but don't discount the ability to stay on top, because the alternative is a rolling, bobbing, slow ride, which generally is what makes folks uncomfortable, especially if you're stuck in it a while. Most can take a little low speed pounding if it's short lived.
     
  2. nzboy
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    nzboy Senior Member

    I often joke the only boat I would want to be in heading out of Bluff in would be 20 plus metres .That being said have a look at ranger tugs .Depending on how much you want to spend there are a lot of worthy 2nd hand boats. eg carver voyager for 20k also a lot of Pelins and Vindexs which are all solid boats in the 9-11metre range that can easily handle a group of people and were designed to handle some rough going because of their deep v hulls Its interesting most most local boats Stabicraft and Image boats have settled on 22 degree deadrise for good reason
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    I think you need experience in the area to gauge what is required, but, from Wiki....
    The strait is a rough and often treacherous stretch of water. In 2006, six muttonbirders died when their trawler sank while returning to Bluff. From the years 1998 to 2012 there were a total of 23 fatalities in the Strait. John van Leeuwen swam it on 7 February 1963, in a time of 13 hours 40 minutes.
    :eek:
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    There are White Pointers down there, and the idea of donning wet suits and swimming the Strait, is strictly for the hairy-chested.
     
  5. FoveauxSailor
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    FoveauxSailor Junior Member

    Mr E - the media (including the internet etc) is a funny thing and what we learn from it is often lacking in multi dimensional input or consideration !! Our sharks don't bite - well there is no record of anyone being bitten anyway.

    Yes Foveaux Strait is treacherous when it is rough AND your vessel is operated outside of its design parameters, or in an unsafe manner. Hence my development of a Statement of Requirement, which I hope to refine from what I learn from this thread and a wide variety of other inputs. This knowledge will be a big help in informing the safe operation of the eventual vessel.

    Personally I think Foveaux Strait is like any other body of water, not to be feared but definitely respected for its particular characteristics.
     
  6. FoveauxSailor
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    FoveauxSailor Junior Member

    PAR - thanks for taking the time to (re) explain the "low speed plane" concept for rough water, that makes a lot of sense and I need to think about and discuss the performance of some of the local deep-V designs with your thoughts in mind.
     
  7. whitepointer23

    whitepointer23 Previous Member

    Whitepointers are said to increase a swimmers speed 10 fold.:D
     
  8. groper
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    groper Senior Member

    I would have thought a LDL type hull would be good for this sort of thing... I would be going for maximum waterline length that your budget allows. If enough power is installed you should get your 20kts cruise on calm days and it will also perform well in the low teens on the rough days... Something like a simplified Irens "range boat" if installed with an appropriate small turbo diesel will give you great fuel economy if you're r doing th journey frequently ...
    [​IMG]

     
  9. tom28571
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    tom28571 Senior Member

    I'm finding it confusing to follow the same subject on two forums, particularly remembering what was said and where.

    Anyway, I thought this was interesting.

    Issued by MetService at: 10:37pm Saturday 5 Sep 2015
    Valid to: Midnight Sunday 6 Sep 2015
    Forecast: Foveaux Straight

    *** GALE WARNING IN FORCE ***
    Southwest 30 knots, rising to 40 knots early morning. Sea becoming very rough. Southwest swell rising to 6 metres. Poor visibility in occasional showers.

    Three Day Outlook

    Easing Monday morning southwest 25 knots and Monday evening 15 knots, tending late Tuesday northwest 15 knots. Rough sea easing. Heavy southwest swell, easing Tuesday.

    Any interest in a little cruise? Ok, Ok, I'm being contentious but I'd wait until Wednesday to get back to South Island..
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Catching the fast catamaran ferry looks attractive to me, but I'd suspect there have been some harrowing stomach-churning trips on that one !
     
  11. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Get a MacGregor.:D
     
  12. PAR
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    PAR Yacht Designer/Builder

    I designed a small boat specifically for Storm Bay in Tasmania and the conditions sound quite similar. Design features included more freeboard, more pronounced entry and other considerations, to keep the boat handlable in widely varying conditions. The client suggest he could head out in relatively nice conditions and once he reached certain portions of his operation area, things could fall apart in minutes and he's working in a modest gale. The boat was designed to have a wide range of operation, from slow semi plane to moderate plane speeds.

    The idea being, to keep him on top of the water at say 10 - 15 MPH in rougher conditions, while working in full plane mode in the low 20's, when this was practical. It's one thing to have a design that can take whatever comes, but if you're restricted to 6 - 7 MPH progress for a few hours at a time, you're going to experience too much motion in small craft, so my thoughts where to at least double this speed, halving the time spent in a nasty soup, so he could get back to shore without offering his lunch in payment.

    Deep V designs generally offer a better ride, but you need more power and they require higher speeds to hold them in this mode. The design I came up with wasn't a true monohedron, but it was close, with modest deadrise (about 12 degrees) and significant chine and strake flats. I also had a deeper than usual forefore, so the steep deadrise forward would help part the nasty stuff, instead of lifting clear and causing pounding. It works well and reports suggest it hasn't been difficult to operate in these waters. He has been caught out in short steep seas and lots of wind, but there's always going to be some conditions a design will just have trouble with. He reported a following sea made him chase the helm for an hour or so, but nothing unusual and he was grateful he was able to make shore at 12 knots, instead of puttering along a 5.

    In the end, it sounds like the OP's requirements will likely need a custom or semi custom design, unless some of the local professionals can help. It's not unusual to see one or two designs predominate a fishing community, simply because it's found to work the best for local conditions. The real problem is the subjective nature of the "opinions" of these locals, who likely don't know diddly about hydrodynamics. They may not need to and just know what works, but a little local research might get the design search on a narrower focus, which would be a big help for the OP.
     
  13. tom28571
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    tom28571 Senior Member

    I guess we do not disagree so much after all Paul. If I were to attempt dong this with a Bluejacket 28, the bottom would look just like that. It does have 12 degrees deadrise at the transom and I would drop the forward keel to get the sharper entry you suggest. The rest is already there except my aft chines work to hold the bow down to promote early planing and keep the boat on top of the water as you said.
     
  14. FoveauxSailor
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    FoveauxSailor Junior Member

    Thanks for the thoughts guys, I know that you probably feel you are going over ground much covered, but for those seeking answers context is everything and hearing/seeing your "ideas" is really good.

    I did chuckle about the weather post of Tom's. Yes a lot of our forecasts look like that (and this one is kosher, we are in the middle of a fairly severe late winter storm that is covering the whole of NZ) but they are also risk adverse and for every other one you see like this, there are windows where a nice crossing can be made - hence my interest in speed.

    The fast ferry's that operate in the Strait are very very suitable vessels, the current pair having been in continuous service since the mid 1990's. Here is the Foveaux Express (23x8 metres, 25 knots cruise) in the "the rip" at the entrance to Bluff Harbour on a pretty rough day. The rip does get bigger than this but one can nearly always go around the edge of it. I have made a lot of crossings on them, none in really snotty weather. They usually cancel sailings in much above 35 knots, and sometimes a lot less in particular sea states. http://www.marinetraffic.com/ais/de...9/mmsi:512099000/imo:0/vessel:FOVEAUX_EXPRESS Incidentally a skipper once took the first of these sisterships (slightly smaller than these later ones) out through the rip in similar conditions, and tried to punch it through. He took out a front window, flooded the passenger deck and got the sack. I am surprised at this photo, 50 metres closer to the far shore you can see is always a lot smoother.

    I have been caught once in Otter in a genuine 35 knots that came up about 1/3 of the way across the strait. It was very unpleasant, triple reefed, storm jib and engine required to tack, luckily I made it into the shelter of the Island after only a couple of hours (and shortly thereafter was in light conditions again under full sail).

    I don't care to repeat the experience, and even less expose kids etc to those sort of frightening conditions, hence my interest in speed.
     

  15. nzboy
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    nzboy Senior Member

    A locally built foveaux commuter

    Stabicraft_2900-Pilothouse_004.jpg
     
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