I'm to design a canal cruiser that can handle high seas...

Discussion in 'Boat Design' started by solitaire, Aug 17, 2012.

  1. solitaire
    Joined: Aug 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Dalarna, Sweden

    solitaire Junior Member

    Not necessarily fast per se, but certainly I'd like it to push on a little quicker than a single hull of displacement design. Could you explain what SOR is in this nomenclature - for one thing I'm 100% certain it's not Sex Offenders Registry :p
     
  2. messabout
    Joined: Jan 2006
    Posts: 3,275
    Likes: 417, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    SOR.. Statement of requirements or a list of requirements. This is distinctly different from a statement of wants or desires.
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 494, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Considering some of the participants here and their understanding of SOR, you may be much closer to correct in your interpretation of this acronym. It stands for Statement Of Requirements and is essentially the design goals established between the designer and owner, as the plans begin the design process. Without a clear cut set of goals, you can't know if the specifics of the design decisions will meet them. Sobriety Or Relinquishment may be a better way of looking at it.
     
    1 person likes this.
  4. solitaire
    Joined: Aug 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Dalarna, Sweden

    solitaire Junior Member

    It is smaller because on one hand of practical and logistic reasons and on the other should I max out the specs we'd really be pushing it. E.g. those 4.5m I mentioned is the width of a part of the most local canal where the waterway is infact blasted right through the bedrock - which means rough edges and God knows what the bottom is like.

    No, none that comes to mind. Most conventional motor yachts are mono hulls of planing design, to my knowledge. These usually roll pretty profusively to my experience and are kept on course by the thrust of their engines (at slower speeds or engine failure they're in the hands of the four winds, really).

    Then a typical boat designed for canals are more like narrowboats or barges - also monohulls but of displacement design, in the case of narrowboats flat bottomed and don't accept rather rough seas.

    Ideally should one or two people stand on either side of the boat or in the very fore or aft, which isn't that uncommon when passing through a lock, there should be a very minor movement in roll or yaw. A displacement design should take care of that but is limiting in velocity and most likely would roll and heave if using a conventional bow. Wave-piercing designs could be an option there.
     
  5. solitaire
    Joined: Aug 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Dalarna, Sweden

    solitaire Junior Member

    Good point there. Yes: it's prime design features should be sea handling. But that's where the dilemma comes in, isn't it. It's relatively easy to design a boat for rather high seas and at certain velocity, but how does it fare at slow velocities, smooth seas and when the displacement and centre of which is changed.
     
  6. solitaire
    Joined: Aug 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Dalarna, Sweden

    solitaire Junior Member

    You know you are quite correct on that. My sincere thanks. Spelling has a tendency of being confused and then that confusion spreads until you no longer know what is what.

    I would say the width of the canal is 4.5m which should make it just under 15 feet. But as previously stated that is bedrock and I'm uncertain about the quality of the bottom and what ever is below the water surface. All the more crucial to leave some room for manuevering the craft.

    If reinventing the wheel is in reference to the design of boat I'm looking for I suppose some invention or some irregular combination of design principles may become necessary to meet with the criteria. Then let's see how close to this vision of mine the completed vessel will in fact turn out.
     
  7. solitaire
    Joined: Aug 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Dalarna, Sweden

    solitaire Junior Member

    A bit of an addendum to the original post:
    Canals of this country and probably other Nordic countries may be a bit different from those in the UK, the Netherlands, France... and so on. Most of them are basically longer or shorter links between lakes, some of them rather large, and the Baltic sea.

    Some canals, such as the Strömsholm Canal (our most local one), an existing, natural waterway (Kolbäcksån/ Colebeck river) was utilised as its backbone and only bypassing rapids and otherwise deceptive streches of navigation. As such there can be the occasional obstacle in the water, surveyed and unsurveyed.

    Those larger lakes and the fjords and estuaries of Baltic sea coastline are large enough to produce some quite challenging waves. E.g. Lake Vättern didn't accept the 8m Koster keel (streched and low draught keel) sailing boat we used to have and kept throwing us back.

    The boat we have at present is something of a converted sailingboat (with a conventional keel) for stability, but wakes of other boats and waves e.g. of lake Mälaren makes it prone to roll beyond any level of comfort. Not that I get nauseous but even fairly secured items seem to scatter around which can be annoying.
     
  8. erik818
    Joined: Feb 2007
    Posts: 237
    Likes: 21, Points: 0, Legacy Rep: 310
    Location: Sweden

    erik818 Senior Member

    Solitaire,
    I'd suggest that frequent canal use add to the specification regarding robustness and width. Narrow is preferrable and the boat shouldn't be damaged when bumping into other boats or lock sides at moderate speeds. This probably rules out a trimaran. Except for the speed requirement, a displacement monohull would fit the bill but you already know that.

    I find it useful to not only list absolute requirements, but also include realistic desirables with the degree of desirability graded. The list will probably mature while you're looking at different options. It would be helpful if you could give a better indication of the size you envision. Do you have an idea of the displacement that will be needed? Anyway, the speed requirement of up to 15 knots and an allowed width of 3 - 4 m indicate that a cat should be considered.

    Erik
     
  9. troy2000
    Joined: Nov 2009
    Posts: 1,743
    Likes: 170, Points: 63, Legacy Rep: 2078
    Location: California

    troy2000 Senior Member

    Sounds like the woman who went to buy a horse, and told the trader, "it must be strong so my husband can plow with it. It must be fast enough for my son can race it, but gentle so my daughter ride it. And of course it must be carriage broken, to take us to church on Sunday mornings."

    The horse trader nodded his head and replied, "of course, Madam. And will Madam also be wishing to milk this horse?"

    Sorry, Solitaire. I couldn't resist....:D
     
  10. Frosty

    Frosty Previous Member

    You think high seas is easy and a canal is difficult.

    Have you ever been on either?
     
  11. DCockey
    Joined: Oct 2009
    Posts: 5,202
    Likes: 600, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Perhaps you might look at what Solitaire has actually stated as his desires, rather than what someone else claims he wants.

    For speed Solitaire said "It's most likely to have a maximum speed of perhaps 10-15kt on open water" which for a 6 meter to 8 meter long motor boat doesn't sound like "a really really fast boat" as his requirement was described by someone else. The only statement from Solitaire about capacity which I can find is "having the capacity to take 1-6 people" which sounds reasonable for the size boat he is considering and does not sound like someone else's claim that he wants to "carry an artic lorry and a house".

    He does want greater initial stability than typical in 6 meter to 8 meter long motor boats, which seems to align well with his consideration of multihulls and similar. "you should be able to walk around the boat and it having the capacity to take 1-6 people without leaning over in roll, yaw or altering its draght considerably." and "Ideally should one or two people stand on either side of the boat or in the very fore or aft, which isn't that uncommon when passing through a lock, there should be a very minor movement in roll or yaw."
     
  12. DCockey
    Joined: Oct 2009
    Posts: 5,202
    Likes: 600, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

  13. Ad Hoc
    Joined: Oct 2008
    Posts: 7,491
    Likes: 1,373, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Your assumption being that some posters cannot interpret a simple request?

    Even at 8m in length that is Fn of 0.93. I wouldn't call that "slow" in terms of a canal going SOR. Most have a max Fn around 0.3-0.35. Considerably different.

    Typ. Canal Barge here:

    typical barge GA.jpg

    Somewhat different :eek:
     
  14. Ad Hoc
    Joined: Oct 2008
    Posts: 7,491
    Likes: 1,373, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    :D:D:D
     

  15. DCockey
    Joined: Oct 2009
    Posts: 5,202
    Likes: 600, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    My experience is that some posters can and do mis-interpret or mis-represent simple requests and statements of others. It is not clear why they do so.

    Let's look at what Solitaire actually said in his first post:
    "It's most likely to have a maximum speed of perhaps 10-15kt on open water."
    He didn't say 10-15kt in a canal; he said in "on open water" which usually means on a lake, bay, the sea, etc. A Froude number of 0.93 on open water is not particularly high speed. Perhaps you missed the words "on open water"?

    Not all boats used on canals are "canal barges".

    If I confined my view of canal boats to the boats I see in British canals then something like the illustration above might be what I thought was meant by a canal cruiser. In Canada and the US at least, a much wider variety of craft are used on canals including houseboats, very high speed motorboats, blue-water capable yachts, pontoon boats, runabouts, and almost anything else which will fit through the locks, particularly those which connect more open bodies of water. I have also seen a variety of boats on canals in Sweden.

    Perhaps you jumped to the conclusion that Solitaire wants what you consider to be canal cruiser, ie a canal barge, based on the title of the post, and then tried to force his statements to that mistaken assumption. There are incompatibilities between his requirements and your assumption of what a canal crusier is so you make a negative comment about Solitaire's ideas, rather than recognizing that your initial assumption was incorrect.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.