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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Monday, January 21, 2008

Spinning Brodies and Flipping Dinghy's

Ummm... Raoul, I think that the Sailing Dinghy would perform better if it was right side up :-)

The crew of Free Spirit, joined with Raoul and Margaret, decided to take our first real river trip. About 2 miles up river, Blayde noticed that his dinghy was catching a little air, and he was concerned that it might flip over. After speeding up a little it started doing it even more... So he went to Dad and told him of his concerns. He was not convinced when he was told that it should not be a problem. I was down in the cabin during this discussion and had no idea what was going on until I heard yelling and complete chaos on deck. I emerged just in time to see Raoul launching the Sevylor overboard, Blayde's dinghy flipped over, and the contents of the dinghy floating down river. Here is 'the rest of the story"!

It ended up that Raoul and Blayde jumped ship to attempt not only the rescue of all the stuff that was dumped out, but to also right the dinghy. All the rest of us (including the ship's photographer), watched and offered probably way to many suggestions on how it could be done better :-)

Well, now what do we do???

Here is the dinghy, almost righted.... It is hard to see, but Raoul was having to stand on it while at the same time trying to flip it over.

Blayde, in the Sevylor, grabbing whatever he can, before it floats away!

YAH!! Let the bailing begin :-) I gotta hand it to Raoul. He was really stoic, brave and super wet after this was all done. Thanks dude! Also, Blayde exhibited safe & amazing kayaking skills during the whole experience.

After getting everything re-secured, we sent Raoul & Blayde back towards Glades in the Dinghy, under sail only because the engine had been drowned. They were searching the shoreline for stuff that was in the dinghy before it had flipped over. Shep donned his tri- corner hat for their cast off.

Shep takes the helm while he waits for his hot chocolate. It was really chilly out there that day (maybe even as low as 50)!

Spinning brodies?? In a sailboat in the Caloosahatchee River?? What in the world??
Thanks to her modern under body, Free Spirit has the ability to spin on a dime. With the wheel cranked, you can turn completely around and never leave your own wake circle. Margaret really enjoyed testing out this theory :-)

Tamer takes a little break on the bow sprit.... When we left Glades that morning, he had been trying to come up with a drill for the crew to do while we were underway. Like maybe a buoy overboard that we would need to retrieve.... He definitely got more than he bargained for!!

As we come around the final bend, we see Raoul and Blayde waving franticly from the shore. Apparently, due to the strong wind conditions, the boat had become fairly hard to control. During a close to shore jibe, with all the sails raised, the tiller broke off in Raoul's hand. So then they had to beach the boat and wait for us to arrive. So this time, Shep was off in the Sevylor to tow the dinghy back to the safety of Free Spirit!! It was a very exciting and fun filled day for all of us :-)


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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 =