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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Thursday, March 01, 2007

A Slice of Life

So we found out that even if you do wear safety goggles while grinding, pieces of burning slivers can get through. Tamer's eye had been bothering him for a few days, and it wasn't until the 4th day that the metal embedded so that I could see it. We thought that maybe, because it was steel, a good magnet could remove it. Unfortunately, it did not work, and we took the day off to go to the eye doctor, who cut it right out. Everything was as good as new a couple of days later!

My Mom was down for a week visit, and was a great help! I got 4 treatments of acupressure for some back trouble, the kids got some Nana time, and we all enjoyed many wonderfully prepared meals ;-) Thanks Mom!!

Valin & Drake hanging off of "the queen's" staircase.

Blayde, using some free time to make Margaret an earring out of copper.

Olivier of P'tit Louis hanging out with their cat Squat.

Matt and Margaret taking a break from the GRIND, and relaxing on Drummer's Aft deck. They have moved right into the boat yard lifestyle, and we are really stoked about their new boat!

We gave Drake this bar for Christmas about 3 years ago, and now we have installed it hanging off of the bowsprit for all of them to play on.

So one day after having some chex mix with lunch, Valin appears and announces that he is now Mini Margaret! He had half circle pretzels in his nose, ears and tongue and she was very flattered :-)

Blayde, exhausted after a hard days work; fell asleep with the "A Mariners Miscellany" book in his arms. He says that it is like the Bathroom Reader series, but about sailing.

Drake and Nana watercolor pencil painting the sunset by the River.

~ Sunset on the Caloosahatchee River ~


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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%


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

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. =
  Prop rpm max =
  Prop rpm cruise =
  Pitch =
  Diameter =
  Static Thrust =
  Cruise HP =
  Cruise HP% =
  SL Ratio =
  DL Ratio =
  SL Max =
  HP Required =