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.....

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!

Sunday, February 22, 2009

To Tow Or Be Towed..... That Is The Question!

Hmmm... Well here is the section on "Tow"..... We were just North of Titusville a few miles when this little sailboat raced past us at about 7 whopping knots, and ran hard aground. We called them on the radio and asked them if we could offer assistance in any way. Here is Paul in the dinghy (getting completely soaked) running them a line to tie off to the bow of their boat, from our stern.

It is quite dangerous to the crew on board, and can be hard on the mechanics to perform this operation. We had to attempt 5 times, without running ourselves aground before we were successful in getting them free.

It took about an hour, but we felt really good that we saved them about $1,000!

Soooooo, this is where we were really thankful that we had purchased Tow Boat US towing insurance last March! We were just turning into the St. Lucie River, on the way to cross Lake Okeechobee, in 10' charted waters, and we ran aground. Now, let me tell you..... We have run hard aground probably about 10 times since we have been aboard. And because I have the Master Captain, we were always able to free ourselves under our own power. This time was a little different from the initial huummmppphhhh of hitting.

So after about 30 minutes of trying to free ourselves, I mentioned to Tamer that this might be the time to get our $125 back on the insurance. Of course, he would have rather waited until high tide, set off some anchors, and done it the old fashioned way. I, on the other hand, really wanted to make our scheduled anchorage, and make less work for him and the crew. Tow Boat US showed up about 6 minutes after the call and got to work.

Hey, ya know, this is pretty awesome!!

After trying to haul us off for about 10 minutes, the Captain of the Tow Boat US vessel allowed us to power up and aid him. It ended up taking all the power he had, plus all of ours to get us free of this shoal. Of course, I felt justified in the purchase of the insurance, as the bill for this would have been $811! It is too bad that it is not offered outside of the US where we are headed very shortly!


Anonymous Anonymous said...

Hello, Everyone!
It's Paul's mom, Caroline. I hope you're getting this. I noticed the new photos and figured you are now able to get online, at least once in a while. I teach first grade and was wondering if our class could carry on some kind of correspondence with you all. Let me know what you think - it it's even feasible at this point. If not, our class will be together next year in second grade, as we loop up together.
If you ARE getting this -- hi Paul! I love you and miss you!

10:03 PM  

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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 =