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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Wednesday, June 27, 2007

Portholes Are In Cap'n

Here is Blayde diligently die grinding away on one of the 11 portholes for the boat. Our goal was just to remove the heavy corrosion, as keeping them polished would be a full time job we do not have time for right now.

This shows in more detail the bronze corrosion that needed to be removed before installation. Blayde has learned when to have an easy hand with the power tools, and is very good at this type of work.

Here is Tamer cutting mounting plates out of plywood with Nathalie's handy dandy roto zip tool. And there is Nathalie in the background beginning work on the skylight for the cargo hold.

When the portholes were installed originally, they were not done correctly. This led to a huge amount of corrosion on the outside of the hull, and the interior mounting surface. Also, a lot of the screws either broke off, or had to be cut when we took them out.
Tamer bought this stuff called 'starboard' that comes in sheets and is 5/8" thick. He then cut them out as shown above and drilled holes for the mounting screws to go through.

This is the plate that mounts on the exterior of the boat.

Valin, screwing the plates on, while Tamer is inside holding everything together. He was pretty nervous the first time working on the ladder, but it didn't take long for him to overcome. He did a fantastic job!

As you can see, the screw go in through the outside, into the starboard, then the plywood and finish in the port hole. When we removed them in January, there was no starboard, or plywood mounting surface for the interior walls to attach to.

These are the 3 on the port side of the Focsul, and there are 2 on the starboard side. The cargo hold has 1 on each side, the galley has 1 over the stove, and the aft cabin has 3 installed.
One more thing sealed up on the boat!!


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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 =