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.....

Contributors

Google
 
Web sailfreespirit.blogspot.com
If you are joining us for the first time, click here for an introduction!
Books and more, at the Schooner Free Spirit Chandelry
Clothes and more, at the Free Spirit Logo Shop!

Monday, October 23, 2006

A moment to pause and reflect.

As the carpet of life unrolls before me, I sometimes have the occasion to take a few moments and ponder the infinite. This is one of those moments.

Some of you have recently joined this blog. I would encourage you to go back to the beginning, and read at least the very first post. Sometimes it is easy to get caught up in the hustle and bustle of life, but it is sometimes as important to focus on the destination as it is to revel in the process.

Some of you have watched our story unfold since long before the first post. To these, our old friends and faithful family, I would like to extend our gratitude. Your love, belief, and support are as much a part of this story as are our day to day triumphs and tragedies. Thank You.

Some of you have hosted us or helped us along on our journey. You have expressed your affection and support as much through action as words. To you we owe a debt of gratitude, and look foreword to the day when we can do the same for you and others.

Words fail me to express my gratitude to each and every one, and I only hope that I can be of equivalent service. To whom much is given, much is expected. I take some comfort in the knowledge that I have been a help and a loyal friend to many, but I remain humbled.

Before too long, our gypsy odyssey will draw to a close, and we will have our sea legs firmly under us. at this point, it is my hope than many of you will take the time to join us and share a bit of our adventures, whether your taste runs toward the tame canal cruise or the bold ocean crossing. It is much for this reason, the ability to share our dream with you, that we have undertaken this voyage of discovery. I hope you come along.

Farewell, gentlereader, and may the fair winds of fate find you rested and well.

posted by CT | 2:01 AM

0 Comments:

Post a Comment

<< Home

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 =