Rowing Skiff Design Tango 17 vs. Heritage 18

Discussion in 'Boat Design' started by SailorDon, Oct 23, 2016.

  1. SailorDon
    Joined: Apr 2013
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    Location: Livingston, TX

    SailorDon Senior Member

    In evaluating the design of a rowing skiff, I desire the best performance for my rowing effort. (I don't want to be dragging an anchor while rowing.)
    I have to be able to buy it "off the shelf". No custom boats and I am not a boat builder.

    Two commercially available designs are the Tango 17 and the Heritage 18. Both have websites with a lot of details about their designs.
    From their websites, here are their basic specifications.
    [​IMG]
    Both designs have built-in buoyancy and are self-rescuing.
    Both are double designs that can be rowed as singles.

    The Tango 17 appears to be a bigger, heavier, beamier, greater capacity, slower rowing skiff.
    But specifications can be deceiving.
    2 months ago, I bought a carbon fiber Heritage 18 double with sliding seats and 9.5 ft. oars. It was about $1,000 less than the equivalently equipped Tango 17.

    I was surprised that the Tango 17 lists 5.5 knots (6.3 mph) as their top speed. I can hit GPS max. speeds over 7 mph (6.1 knots) routinely, but not for long. Perhaps 5 strokes.
    A typical rowing data report is shown below:
    [​IMG]

    If there are any Tango 17 owners in the Houston, TX area, I would like to meet up and perhaps do some in-the-water comparisons.
    I would also like row my Heritage 18 in the doubles configuration. I have all the equipment, but can't find anyone that knows how to row. :(
     
  2. messabout
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    messabout Senior Member

    The 18 footer is clearly the more desirable of the two if top speed is the aim. It is lighter, longer, narrower. It is also likely to be rather expensive if it is actually a carbon or Kevlar hull

    The pictures show a lovely wine glass transom. One of the pix suggests that it is being trimmed with a slight bow down condition. That is a factor worth exploring.
     
  3. SailorDon
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    SailorDon Senior Member

    Max. speed is definitely a performance criteria. Also high on my performance criteria list is a high cruising speed that I can maintain for 3 or more miles.

    Another criteria is weight. Although I can trailer the 200 pound Tango 17, I could not load 200 pounds on the roof rack of my truck. The 90 pound hull of the Heritage 18 can be transported on roof racks.
    [​IMG]

    With respect to the "bow down" trim condition, I find that under maximum load at the end of the power stroke, the bow digs into the water.


    This video shows a hobby horse motion from bow to stern with each stroke of the oars.

    Additionally, the transfer of my weight to the bow at the end of the power stroke also makes the bow dig in.
    With less aggressive rowing, the "bow down" trim is not so drastic.
     
  4. SailorDon
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    SailorDon Senior Member

    When the oarsman outweighs the boat by more than a factor of 2, the sliding seat motion makes a significant difference in the fore/aft trim.
    From this morning's rowing exercise, here is a screen capture from a video showing the end of the recovery stroke, just prior to the catch.
    Heritage 18 Carbon Fiber Double October 26, 2016:
    [​IMG]
    The bow is so far out of the water, you can see the knuckle where the stem joins the keel.
    If I could bend my knees more, I might be able to get the entire front end of the boat out of the water. :D
     
  5. messabout
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    messabout Senior Member

    With a sliding seat some pitching is to be expected. Your boat appears to have a lap strake configuration. Classic stuff but maybe not the absolute slickest of hull configurations. But the bigger consideration is that it can be built lighter than a smooth sided boat while maintaining equal or better torsional stiffness.

    If a boat must push aside a pound of water for each pound of displacement then your trade off is a good one.

    Enjoy the delightful ride.
     
  6. rower mike
    Joined: Oct 2016
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    Location: BC Canada

    rower mike Junior Member

    Hi Sailor Don...

    as per messaboat, the longer slimer boat is almost always faster. in this specific case most likely yours... (good choice)

    but if you're all about speed?? i'm wondering if you've looked at actual openwater shells etc... like those from MAAS, Echo etc... the merry wherries etc...

    or if those aren't what you'd call a "rowing skiff"?? in that you want something a little safer/versitile

    either way... i looked at your video
    typical rowing rigging for sliding seat rowing usually involves lengthening your inboard to create about 3-4 inches of overlap between the handles... ie a lower gearing ... it didn't look like you were set up that way....

    if you haven't already tried it that way...
    it might allow you to sustain a higher cruisings speed/ higher rates due to the reduce load. but only do that if the geometry works for you... ie you can still adjust everything else... so you still pull in at a comfortable height. and there is a slight trick to making that work out so you don't loose a thumb... especially in rougher water.

    Oh... & Hi to everyone...
    this is my first ever post here... long time lurker and gatherer of everything rowing skiff related i can find on the web at all the usual sites like... duckworks, wooden boat, small boat mag... and all kinds of others especially FLO-MO 's site.

    used to row competitively up here in Canada, then i coached,
    i've built a couple marine ply glued lap rowing skiffs ... based on the LHF rowboat... (sort of like Tango / Hertiage) used sliding seats in both, i like to fish, stop and stand to stretch out (and fly cast at times) ... as well as go on some camping/rowing trips with them... so i want something that can do all that AND go fast.

    the longer one is about 18ft 10" LOA 40inches wide - and i just finished building it...
    am getting sustained speeds of about 5 mph
    (multiple timed rows over a 5 mile google earth route)

    but i have the same basic problem... how does that compare to another boat and how do i know what's the truth or an exageration... or if their predictions for their boat are all based on a rower 40lbs lighter than me, 30 years younger and a hell of a lot fitter!!

    i'd really hoped to get 6 mph out of the 18ftr because i've been seeing lot of articles claiming that there are rowing skiffs out there that are achieving that (and more)... and am now trying to make sense of them all.

    For sure there are some that are achieving it. (ie the finnish sulkava boats).. but like i say.... i also want something more versitile and is it really possible to squeeze another 15 to 20% more speed out of say a Heritage and or a LHF type hull
     
  7. SailorDon
    Joined: Apr 2013
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    SailorDon Senior Member

    No. I'm not all about speed. But I don't like to be forced to go slow because I'm dragging an overweight clunker of a rowboat through the water. :(
    I've never rowed a lifeboat, and I don't really want a lifeboat. And a lifeboat won't go on the roof racks on my truck.

    I am about taking the ladies for a row if you catch my drift. :D
    That ain't going to happen in an open water shell. Where do you put your passenger, cooler, beer, wine, etc.?

    Overlapping oar grips does not work for me. Too much rough water rowing. I'm struggling just to keep both oars in the water! :)
    The attached pic is from yesterday's rowing session.
     

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  8. rower mike
    Joined: Oct 2016
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    Location: BC Canada

    rower mike Junior Member

    yep - we're on the same page boat wise... open water rowers ... room for a passenger and/or gear if required... and both want faster boats... and both of us are still asking... how do we really know if one rowboat that does what we want is really faster than another... besides picking the longest and skinniest one we like... and/or rowing both with a GPS

    the closest thing i've seen in that regard is at FLO-MO's site .... he has a excel spreadsheet you have to download that he built in which he compares all kinds of rowing designs using drag/ resistance predictions that he got by loading all the data he could find (or his best guestimate) into some design software..
    It crunched the actual #'s and provided performance predictions.... and he's graphed those out in excel...

    Sooo... you got a buddy who can do that??
    I can't .....yet ... but definitely want to learn how... and have been flailing away trying learn it and to compare my boat to Flo-mo's results. done using some rough cals and by guess and by golly estimates that i'd really really like to bounce off someone who trained in this stuff.

    Am really hoping someone will chime in here ... this is a design forum after all ;) ;)

    yeah.... keeping your oars buried in rough water can be tough regardless of how you're set up fixed seat, sliding seat, with or with-out overlap... been out in the condition like those shown in your photo alot and can manage it with overlap... but yes i totally agree it is easier without...

    i mostly row on Okanagan Lake up here in Canada (my home lake) - its 70 or so miles long and lots of reaches/fetches are 15 to 30 miles long so it can be rough.

    I also regularly row/camp on some other big lakes up here as well, one is actually pretty remote and designated park that is restricted to human powered craft only. the pic is my first boat with the far end of the North Arm in the backgrd.
    http://www.env.gov.bc.ca/bcparks/explore/parkpgs/wg_murt/
     

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  9. SailorDon
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    SailorDon Senior Member

    The "skinniest" rowing skiff is easy to determine. It's the one that won't tip over when you get in or out of it at the dock.

    The "longest" is harder to determine. The drag on the hull is a combination of skin friction and wave making resistance. Too short and you waste your energy into making a big wake. Too long and you drag a lot of extra water in the boundary layer, slowing you down.

    How do you determine the optimum performance with respect to water line length? On my Heritage 18, 4.5 mph is an easy cruising speed. 5.0 mph is a big increase in drag. The effort to maintain 5.0 mph is about twice the effort to maintain 4.5 mph. The visual indication is very little wake at 4.5 mph. Lots of wake at 5.0 mph.
     
  10. rower mike
    Joined: Oct 2016
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    rower mike Junior Member

    completely and totally with you on this..
    you want a boat that can go over 5 mph or even 6 mph because it has less drag... whatever combination of "total resistance" that drag might be made of... be it from wave drag and/or skin friction... Me too!!!

    here is the specific location of Flo mo "resistance /drag calculations" i talked about.
    http://flo-mo.weebly.com/resistance-and-stability-comparison-of-rowboats-and-canoes.html

    with the spreadsheet i mentioned... if you get into it... note that the resistance is expressed in Kg... and note that there are a fair number of the designs are predicted to go almost 6 mph and still have what i think?? are pretty low resistances / drag figures (you'll see why i think this later)

    heres another site... but for kayaks...
    http://www.oneoceankayaks.com/kayakpro/kayakgrid.htm
    part way down ... there is a total resistance versus speed chart note that the resistance is in Lbs...

    both show that there are people out there who can calculate this stuff... (again... is anyone else following this who can help??)

    there is also this site...
    http://www.marinerkayaks.com/mkhtml/downloads.htm

    that actually has a drag calculator spreadsheet people can download towards the bottom
    that should calc total drag... at various speeds and i've been in it and looked at it...but its pretty evident that it would take me a huge chuck of time to figure out how to use it...and to actually get it right so i can actually trust the results , espeially if i have to teach myself via trial and error
    get one entry is wrong... Murphy's law of computers.... garbage in = garbage out.
    I kinda have a handle on some of the inputs that are required... but not all of them
    and further i actually want to see the entire formula that it uses all at once... not just have an magic answers appear before me.

    as far as where i'm at with my boat... and what resistance in Lbs or Kg that these graphs use.. really means . this is what i think?? that i know...

    i have a concept2 rowing erg... it can display how hard i am rowing in "watts"
    i set the air damper resistance so it feels like the same load as when i'm on the water... and that keeps me at about the same stroke rate as on the water... then i rowed about 3 different 15 minutes sessions with just a bit of rest between each at about the same pace i think i use on the water.... that turned out to be an overall average 170 watts... (thats a 2min 7sec ish pace/500 m if you are familiar with that erg at all.. but remember that pace is for a pretend racing shell cranking along at about 9 mph and change)

    note that watts is metric... sorry about that ... but that's what i'm most used too... so what follows is gonna use mostly metric...

    the basic physics i know goes a follows
    ( & i know just enough to be dangerous .... so what follows could be totally out to lunch) goes as

    like i posted earlier in this thread... my boat and I regulary do 8 kilometers in 60 minutes...
    i think we can totally ignore the changes in speed that happen within each stroke...
    and assume i'm actually travelling at constant average speed ... if speed is constant....
    the power/force i put in to moving at any given time, has to be exactly equal to the drag force on the boat trying to slow it down at any given time... other wise i'd would NOT be staying at the same constant average speed.

    so... here we go...
    170 watts /sec is how much power i am generating... Power x time = work done
    so 170 x 60 sec x 60 min = about 600,000 metric units of work... in joules i think

    Now "Work" also equals Force applied x Distance... and i know my distance was 8,000 meters
    so i take that 600,000 joules and divide by 8,000 and get about 75 units of "force" in Newtons)

    now Force = Mass x Acceleration
    now here's the thing ....the acceleration of any force can be fast or slow... but generally everyone is most familiar with effects of Gravity..... so if we throw in the rate of acceleration associated with gravity ie 9.8m/sec we can express the resulting mass in real life terms of mass/weight that you & i work with/feel whenever we pick something up or put it down in every day life ... and then say manly stuff like... that chunk of iron was 50 lbs and i curled that sucker till i felt it BURN!!.

    long story short... i think?? my boat has about 7.5 to 8 kg of resistance at a speed of 8 km/hr.... thats about 16 to 18 lbs of resistance... that seems pretty reasonable to me - i'm using my legs and back and arms... ie 3x as much muscle as a kayaker... i'm guessing my water line beam is like at least 50% or 75% wider than a kayak if not more.... so yeah compared to the total resistance kayak graph from above kayak website... which indicates their boats are generally doing 4.5 knots at 5 lbs resistance.... i think??? i'm kinda in the right general ball park with my understanding of what going on...

    but i don't want a kayak, i want a rowing skiff so that is where the Flo Mo spreadsheet comes in.... it lets me compare my row boats to other mostly rowboat designs... and his evaluations seem to show that there are a fair number of boats that he thinks can go 9 km/hr at 6 kgs of resistance. so that seems to say my boat might be a bit of a dog....
    (Note that for what its worth.... i back calc'd 6 kg's (13lbs) of resistance using Flo Mo's boat speeds etc.... and that seems to work out to what i think is 151 watts of power on the concept 2 rowing erg)

    but heres the thing... Flo mo's performance number are all calc'd assuming the boat and rower in total weigh in at 135 kg.... i'm 6ft 1... 240 lbs fully clothed, my boat weighs another 125 fully rigged including a spare set of oars and i take about another 10 to 20 lbs of safety gear and water with me on most rows... that converts out to about 180 kg if not more... and i don't know how to adjust his results to account for things like that at all..

    same thing with the kayaks, i highly doubt they are moving >350 lbs plus of water out of the way as they cruise along at 4.5 knots...and yet only experience 5 lbs of drag...

    that extra weight also effects the actual water line beam... as more weight make any boat sits deeper in the water.

    would love to know exactly how this kind of stuff gets calculated by a someone that has done it regularly and knows the real ins and outs.... and actual formulas...
     
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  11. SailorDon
    Joined: Apr 2013
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    SailorDon Senior Member

    rower mike:

    It seems obvious that increasing the length will create less drag than increasing the beam.
    The question is, how much length to add to minimize wave making resistance?

    Last Saturday, I entered my solo canoe in the 7.7 miles Greens Bayou Regatta (Houston, Texas) in the Solo Unlimited Class.

    The winner was #78 (1 hr 12 min) :
    [​IMG]

    Sailor Don #69 (1 hr 59 min) :
    [​IMG]

    Look at the difference in waterline length (and max. beam at the waterline).
    The fact that #78 is less than 1/2 my age and built like a professional athlete might have something to do with it, but I attribute his victory to waterline length. [​IMG]

    At my age, I'm lucky I made it across the finish line.
    They should have an "old age" allowance.:)
     
  12. rower mike
    Joined: Oct 2016
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    rower mike Junior Member

    awesome!!! about 8 miles in what appears to be a touring canoe at just under 4mph solo !! takes some effort and dedication ...

    Hull #78 there you go...;) ;) that's another option.... get one and drop in a rowing rig...

    but yeah that type of kayak is pretty fast....

    once and a while there is one sort of like this one
    https://www.epickayaks.com/article/article/v8-pro
    paddling around my regular luanch site... once and while things worked so i could compare my speed to his in my old boat... we were close but he was faster

    haven't seen him out since l launched the new boat though...
     
  13. SailorDon
    Joined: Apr 2013
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    SailorDon Senior Member

    Paddling only, no rowboats allowed in the Greens Bayou Regatta.

    I only mention the following because of your link to Epic Kayaks.
    The SurfSki ICF K-1 had a class all to themselves. First place was 1 hr 1 minute for the 7.7 mile course. (No current.) That is fast!
    [​IMG]
    I think they paddle about 2 strokes per second. These guys are crazy powerful on speed and endurance.
    Way above theoretical hull speed all the time.
    Some of them have their names painted on the side of their boats like WW II fighter pilots.:)
    Perhaps if I paint my name on the side of my Wenonah Voyager solo canoe, I will be able to keep up with those "rocket ships". :D

    My canoe is a Wenonah Kevlar solo canoe.
    Wenonah describes it as "Performance Touring".
    Did I mention I have not canoed or kayaked until 7 months ago?
    Solo canoeing is quite different than the rowing skills that I have developed over the years. You don't do torso rotation in rowing.:rolleyes:
     
  14. rower mike
    Joined: Oct 2016
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    rower mike Junior Member

    found what i wanted... Washington wood craft has Drag calcs as part of their design software.... between that and the Max broze
    I should be able to learn something

    2 strokes/ sec... that reminds me...

    that's another way for both you and i to get some more speed from our skiffs. we should really be trying to cruise at about 22 to 24 spm... i'm lucky if i hit 22 just hammering it and can't really sustain that for more than 3 minutes.

    and am likely at 18 or so most of the time... will likely play around of the Erg... see if i can physically make that adjustment and retain my wattage for extended durations.... though i might skip this too... i hate the erg always have, completely diff feel from actual rowing...

    then it could be surgery on my oars... shorten up one of the sets by a few inches using an old Welsford article about oar length and the Bio row site... as guides
    http://www.biorow.org.uk/RigChart.aspx
     

  15. Oarman
    Joined: Oct 2019
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    Oarman New Member

    I also am interested in the Tango 17 and the Heritage 18 for the same reasons, but my priority would be more for stability than speed. I take people out that have never been on the water before and some are very nervous. Would these boats feel comfortable for two people standing and fishing in? What about standing and shooting shotguns at waterfowl?

    The Heritage comes with an optional tent, but it is very expensive. Has anyone rigged a way to comfortably sleep in one of these boats?
     
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