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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Friday, April 20, 2007

Conversations, Snakes, And Solar Ovens


Multiple conversations.....




Don of Gypsy Queen, and Matt of Drummer having one of many important conversations that take place in the boat yard on a daily basis. Conversation around here is as important as food. Many thoughts, ideas, knowledge and advice are given openly in this environment.




Olivier and ?? at P'tit Louis




Nathalie, Doc, Don, Julie, Matt and Leonard... Changing a bolt on the crane...




Chuck of Jonathan Livingston and Don, discussing hmmmm... not sure :-)




Tamer and Don were using our chainsaw winch to pull Taloa out of the mud at the dock. The water levels have been eerily low; more on that later. As you can see, Glenn is in the background having a conversation all on his own.




I believe that this is one of the "conversations", that led to Margaret buying her new boat Drummer.

She was explaining to me that she really wanted Drummer, but that it didn't seem rational for her to buy a boat that needed work for 15 thousand dollars, even if it was an excellent value. I explained to her that buying a boat was never a rational decision anyway, and that if she felt the boat was her ideal in a sailing vessel, then she should just buy her and put in the work required even if it meant postponing their cruising a few more months.

She bought drummer that day, a sound - if not rational - decision that will lead her and Matt far and wide, as they sail the world on their ideal boat.




There are not very many places that big meetings take place over the design of someone's outdoor shower....From the left, is Doc of Blue Toes, Nathalie of P'tit Louis, Deana and Don of Gypsy Queen and Julie of Gypsy Otter.




Snakes regularly sunbath on the rocks down by the river. I am not sure if we ever properly identified this bugger, but we were told by the locals that it was poisonous.




Slithering away




Doc's solar oven... I never got to taste the roast, but it was keeping around 300 degrees in the afternoon.

posted by CT | 11:07 PM

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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 =