Log of SV Free Spirit and ships company

The chronicles of the schooner Free Spirit and her crew, embarking on an open ended journey upon the great rolling heap. Free Spirit is currently pursuing humanitarian and commercial goals in the Dominican Republic, on the island of Hispaniola. Working under the Ocean Reach USA and Paradigm Research banners, she is serving as logistics headquarters, workshop, and development laboratory for many ongoing projects. This is the log of her journey.....

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Monday, July 31, 2006

Fare thee wells



*Sigh* Not like it was really a surprise for us or the boys, but it is one thing to know that the moment for good byes will come, yet another entirely to live that moment. A bittersweet texture pervades the days, anticipation of things to come tempered by the surety that those left behind us will be missed, and many dearly at that. We try not to think the nagging thoughts, the haunting possibility that for some, this may be the last time we will share. We cannot know what lies ahead with any certainty and though we plan on being back periodicaly, it is not a certainty. We take consolation in the tentative plans for the people we love to join us along the way, knowing that many who give us well intentioned promises to visit will not. Still, the days pass, our departure nears, and the adventures before us draw ever closer. Fare the well, friends, family, and loves - may we see you all again sooner than later, with luck in some idyllic setting, renewing the ties that drew us together in the first place.

Saturday, July 22, 2006

On Free Spirit Projects

In the sandblasting pit, early 2006. First coat of primer on hull.


Though she sailed over from South Africa on her own bottom in 1999 and could be ready for the water with only a day or two's preparations, Free Spirit is very much a work in progress. We've accumulated the lions share of equipment we wamt for her, but all of this will require installation once we get there.

Recently aquired are:

Interphase Twinscope Phased array sonar (like underwater radar)
SSB, Weatherfax, and NOAA Satelite imagery reception capability

Currently designing an auxiliary helm and autopilot system. I think I will build my own microcontroller system to take NMEA data and issue helm commands via a chain drive gearmotor to the wheel shaft. I need a more robust system than can be easily had in the yacht marketplace. This "crewmember" must be more reliable than the regular crew, and be able to steer for days or weeks without rest or worry of breakdown. The solution is to overbuild the system, to make it more like a piece of industrial equipment than an elegant yacht toy. I should be able to build a system that should operate reliably for years on end if I select components with a 1000% load rating (if the gearmotor needs to have 400 inch lbs torque, then I use one rated for 4000 continuous duty). This should be an interesting project.


Then theres the trailer.



Built from a 1942 trailer house frame and axle living its fourth life, now reincarnated as a 14' utility trailer. Previous lives include a flatbed car hauler and a suspension-bridge style log hauler. I wonder what it will be next?

Progress....


Sorry for the long lag in posting, We've been very busy with preparations for our trip. Latest projects include packing all of our stuff into boxes and building a 14 foot enclosed utility trailer, now complete save for the doors.

All the other boats are now sold, so with Westward and Laura Ann II off to new horizons, we can focus on the preparations to Free Spirit.

If you are new here, please check out the archives for some good background info - it's probably even better if you start with the earliest post and read up to here, if you want the big picture. Thanks for stopping by, and may the wind be at your back, gentlereader.

Introducing Propcalc 4.0

Use Propcalc to easily match your hull with your engine, transmission, and propeller
Put the known data in the top fields, then hit the Update button to get the answers.
Results, of course, should be verified by a Naval Architect or qualified surveyor.
Data is provided for three bladed propellers of average type
For two or four bladed props, use the modifiers shown below.

Fill out the fields as follows:

Vessel LWL (ft) = Waterline length
Vessel Disp (lbs) = Vessel displacement
(max) HP = Rated Engine Max HP
Engine RPM max = Engine RPM at Max HP
Engine RPM cruise = Desired or estimated cruise rpm
(Cruise or Max) Kts = Speed to work the calculations for
Slip = Propeller efficience. 45% is average for a displacement cruiser.
Gear ratio = 1: Gear ratio of transmission
SL Ratio Adj. = This value will be added (or subtracted, if a negative value) to the calculated S/L ratio.

Key information:

If the "hp required" is greater than the "cruse HP", you have your cruise RPM set too low for your engine parameters.
If the "hp required" is significantly less than the "cruse HP", you have your cruise RPM set too high for your engine parameters.
If the "hp required" is greater than the "Max HP", then your target speed is too high for your engine/hull parameters.
The S/L ratio is calculated automaticaly based on your input. It can be adjusted if necessary, but normally it should be left alone.
If the calculated S/L ratio exceeds S/L MAX, then the results are likely to be non-predictive. Try a lower speed requirement.
SL Ratios of 1.1 - 1.4 are typical of displacement hulls. Semiplaning or planing hulls can go higher.

Typical propeller slip values:

Sailing auxiliary, barges, etc less than 9 Kts............45%
Heavy powerboats, workboats 9 - 15 Kts....................26%
Powerboats, Lightweight Cruisers 15 - 30 Kts..............24%
High speed planing boats 30 - 45 Kts......................20%
V bottom race boats 45 - 90 Kts...........................10%


Note:

it is possible to get irrational answers by irrational input , I.E specifying excessive speed for hull type and length
Any attempt to exceed hull speed (1.34 times the square root of the waterline length in feet) with a displacement hull are likely
to fail unless the hull is extremely fine (multihull) or otherwise exceptional. In such cases, an S/L adjustment would be in order.

2 and 4 bladed props:


For two bladed propellers, multiply the diameter by 1.05, and the pitch by 1.01
For four bladed propellers, multiply the diameter by .94, and the pitch by .98


PROPCALC
  Inputs:
Vessel LWL (ft) =
Vessel Disp (lbs) =
  (max) HP =
  Engine RPM max =
  Engine RPM cruise =
  (Cruise or Max) Kts =
  Slip =
  Gear ratio = 1:
  SL Ratio Adj. =
   
    Solutions:
  Prop rpm max =
  Prop rpm cruise =
  Pitch =
  Diameter =
  Static Thrust =
  Cruise HP =
  Cruise HP% =
  SL Ratio =
  DL Ratio =
  SL Max =
  HP Required =