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!

Tuesday, April 24, 2007

The Bow Sprit ~ Part 1 ~ Construction

The original bowsprit was easier replaced than repaired. There was extensive, structural corrosion. The new 'sprit builds on lessons learned, with stainless inserts at the wear points and stainless steel anchor roller brackets, as well as a bolt on design closer to the original blueprint specifications.

The 6" by 1/8" square steel tube was impossible to obtain, so I had a machine shop bend 11 gauge sheet into channel so I could weld it together to form a square tube. I also considered using schedule 10 or 5 pipe in 6", but found that that was unobtainium as well, with the Chinese evidently absorbing the entire global supply of petroleum pipeline pipe. Hmmm.

Here, Blayde helps with the spot welding process to hold the parts in place for final welding.

Welding the channel sections together to form the main tube.

The 5/8 plate bullnose, after final welding. This will bear the majority of the loads on the bowsprit.

Bullnose in place, awaiting stainless inserts in the holes.

Reaming the stainless inserts. Here you can see the bullnose, as well as the stainless axle tube and rub plates.

The inner forestay mounting eye, with ears below mounting it to the cutwater. This is a continuous piece of 5/8 plate that bears the loads from the inner forestay directly below to the massive steel cutwater on Free Spirit.

Grinding, showing the stainless anchor roller ears. The stainless axles that the rollers turn on go through stainless steel tubes welded through the 'sprit. The rollers rub on stainless rub plates to prevent paint wear. These details should prevent the damage that caused the early demise of the original bowsprit.

Fashioning the aft end of the bowsprit. Here a stainless eye will attach the after part of the new spar to the deck.

Here, Finished.

View from above.The boys did all of the grinding on the new spar! The entire surface had to be ground to remove the mill scale, which would prevent the paint from adhering as well as it could.

Valin, hard at work. One day, we found him grinding away before anyone else was even awake!

Blayde, focused on the task at hand. Although not pictured, Drake used the air powered die grinder to grind all the stainless parts, his contribution to the grinding effort.


After grinding showing the construction details. Note the stainless inserts welded into all of the attachment points.

More of the details, after the surface prep. The inner staysail attaches to the eye behind the inner forestay. this eye is designed to allow easy caribeaner access for anyone working out on the 'sprit in heavy weather.

Oliver from P'tit Lois helping to foam the new spar with 2 part foam.

Pouring the tricky stuff in.....

....And waiting for it to expand.... what a mess!
The foam will help to keep the bowsprit corrosion free.

More on the bowsprit soon!!!!


Blogger Gayle said...

Smyth Family....back in Fairbanks I eagerly await your latest post. I think I may be living my own adventure through you. For a short moment each night as I read your journals I am momentarily transported to another world. Thanks for sharing this special family time. You inspired me to share my family as well, and have just recently started my own blog. You can see what my "little" family is up to back home at www.twopluseight.blogspot.com I'm glad I had the opportunity to meet your family, and now to follow your travels. Take care. Gayle

4:18 AM  

Post a Comment

Links to this post:

Create a Link

<< 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%


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 =