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, May 02, 2008

The Dry Tortugas

Free Spirit, anchored in the Dry Tortugas, with a resting, non seasick crew! We left Fort Myers Beach on the 21st of March headed out for the Dry Tortugas, our first crossing. It took us about 26 hours from anchorage to anchorage, and we left at 2:30 pm. It is hard to express the vastness of being at sea. It was fun, scary, tiring, wet, exciting, educational and fantastic, sometimes all at the same time! We had 6 foot beam seas (which means that we had 6 foot waves hitting the middle section of the boat). It made for a really uncomfortable, hard to manage vessel. The whole crew suffered from severe seasickness, except that I managed to get away with only about 1/2 hour of it. The main thing that we learned on the trip was that it will be impossible for us to crew the boat with anything less than 3 adults. Although the boys are really hard workers, they lack the maturity to make split second decisions when at the helm. We had no real casualties, and nothing broke!!



A HUGE grouper swimming around under the boat. We had a old fisherman tell us that if you swim in the water with them, they will eat a whole arm at once! Of course after spending a little time with Mel, we realized that he just may be a little crazy :-) It was enough to make the boys at least a little nervous though!



We made new friends aboard the above vessel, Pilgrim. They were a wonderful family, and we really enjoyed spending time with them here. They live in Orlando, and have dreams of living aboard, but for now enjoy any time they can get away and sail. They had 4 children ages7, 10, 12 and 14. Their oldest was in was away on a mission to study sea turtles in Guyana, so we have not met her yet. We look forward to seeing them again, and spending more time getting to know one another.



Drake, getting ready to take the plunge, while on the lookout for man eating groupers :-)



Tamer and Shep rigged up Drake's trapeze bar so that they could swing off the boom into the water. GREAT FUN!



Shep, just hanging around....



~Our floating home~



View from the sea wall.



New anchorages, new birds, new boats and new experiences.



Just a little sea fan....



posted by CT | 4:16 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 =