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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Saturday, December 08, 2007

Mast Modifications

Tamer, grinding the top plate for the radar mount that is now mounted on the top of the forward mast.

The completed mounting plate with Stainless Steel legs.. It looked much better after is was prepped and painted. But, I forgot to get a finished picture before it was in place and WAY up at the top of the mast...

The pegs that were welded on for the plate to mount onto.

Tamer, showing off the new crows nest that was constructed at the top of the aft mast, just above the spreaders.

A close up view...

View from the top...

After being completely prepped, finished, painted and with flooring installed. Raoul is in the process of hand making the rope work that will enclose the area for safety.

View through the top mast collar.

Although not clearly shown through pictures; both of the masts were completely refurbished and painted with 3 coats of the Rustoleum Almond colored top coat. Here I am painting the black stripe at the top of the mast. When you are on board and traveling under bridges and such, most vessels do not have a reference point for judging the clearance that far up in the air. It seems like you are going to hit, even if you have 10 feet or so of clearance. We placed the black stripe 12 inches from the top, so that we have an actual reference point.

The stripes for the same purpose on the aft mast.

The forward mast ready for raising.

Tamer and the boys mounting the compact fluorescent spreader lights on the aft mast. They draw 65 watts of power with a lighting power of 500 watts each.

AHHHH!!! Bright light, bright light!! Even in daylight...

After the masts were raised (in a post coming soon). I was asked by a group of 70 something sailors on this night; Those spreader lights are not your husbands way of showing off are they?? The laughter brought tears to my eyes!! The lights, are by far, the brightest I have ever seen!!


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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 =