Tuesday, May 29, 2018

Cutlass Bearing or Cutless Bearing?

Actually it should be called a  "water lubricated, hydrodynamic standard rubber sleeve bearing."  Yea, that seems a little much.  But, how the name came about is an interesting story.

Mike McCoy's Thoughts on LNVT Resins

I was re-reading the last Tug Talk [Spring 2018] and noticed that orthophthalic was misspelled in the title of the article.  It's correctly spelled in the quote from Net Composites in the body of the article. That launched a teaching script in my brain. It's a hereditary problem. Not that it's interesting to anybody but a science nerd like me but here we go…
First let's review what a polymer is.  The word has two parts poly meaning many and mer which for this tutorial will define as "the building block".  So starting with a big soup of "mers" a catalyst and a stop molecule a chemist can build polymers of specific lengths.  Dimer and trimer would be a two and three starting blocks connected. The stop molecule puts a cap on the amount of mers that can be connected. Alternatively large chains can be created and then chemically chopped up to specific lengths and the purified by separating them by apparent molecular weights.
In the resins you have described there are two starting blocks; iso and ortho phthalic acids (the ph in phthalic acid is silent). They are isomers of each other.  Iso means "the same". But wait! "They have to be different or there is no discussion. Right?" Iso an ortho phthalic acids have the same chemical formula C8H6O4  or better yet C6H4(CO2H)2.  They have the same molecular weight and share many other physical attributes like melting point but they differ in how the constituents are connected to each other. In this case we have two carboxylic acids and a benzene ring.  IUPAC (a bunch of old guys that make the rules for chemical nomenclature) explains the difference by using a naming system that tells where things are connected. So we have benzene-1,3-dicarboxylic acid and benzene-1,2-dicarboxylic acid respectively.
Figure 1 Isophthalic Acid

Figure 2 Orthophthalic Acid
It's extremely simplistic but accurate to say when two isophthalic acid mers are connected they create more linear polymers than when orthophthalic  acid mers are connected. The latter polymer takes up a different three dimensional space. When the polymers crystallize into solids their crystal lattices differ.  This might explain their differing susceptibility to permeation by water.
Lastly but maybe most importantly…  I don't believe that this difference is a significant factor in the blistering problem on some LNVT's . The greater influence on the hull integrity is the quality of the polymers as delivered by the manufacture(s). Some were not as good as others.  Batch to batch reproducibility is hard to maintain especially if many sources where used. The yard would have accepted the product as delivered and not done any in house testing. The guys working in the shop would see the difference and a good crew would adapt accordingly.
BTW…when I took my paint down last I saw clear resin. This makes me believe that Tug E. Bears bottom was possibly gel coated but no pigment was added. I 'll take a better look next time.

Mike McCoy, Tug E. Bear 37VT62

Sunday, May 27, 2018

Corrosion on Elnora's Intermediate Shaft Support

A surveyor, last year, found that Patrick Mitchell's Elnora 37VT37 had a badly corroded plug in the propellor shaft's intermediate bearing.  

The plug was installed inplace of a hose fitting when Elnora was upgraded with a PYI dripless packing gland.  

Patick picks up the story:

My survey last year discovered a corroded bolt that was in the place of shaft hose. This bolt was threaded in as a plug.  Looks square on the top. I took some before and after pics after scraping away green corrosion.  My dripless PYI seal is fine but your newsletter comments are timely for me.  I am tempted to think my corrosion is related to your concerns. 

Mocko Jumbie Drops Asking Price

I have decided to lower my asking price to $75,000 for Mocko Jumbie hull #49. I am working full time as a nurse now and building our house on our days off. I have no spare time to work on the boat, or much less enjoy her. Hurricane season is right around the corner and I really want her taken out of the Caribbean hot-zone for storms. We were very lucky last year, as hurricane Maria claimed dozens of vessels on our island [St Croix].

Liz Harding

Tuesday, May 15, 2018

Burligton, VT Rendezvous--Save the Dates

Just received this nice postcard reminder from Keefer and Bill Irwin, Callisto 37VT19, for the 2018 East Coast LNVT Rendezvous.

This is the Fleet's first ever Rendezvous in Burlington, Vermont. It promises to be a lot of fun! You can find all the details at here.  Bicki and I have RSVP'd in the affirmative.  Hope to see you there.

Monday, May 14, 2018

Spring Commissioning Tip

Hose Attachment to the Intermediate Bearing Support

During your Spring commissioning be sure to check the integrity of the metal hose fitting on the intermediate support bearing.  This fitting supplies raw engine water to the packing gland. Since it's below the waterline, a broken fitting will allow seawater to enter the tug.  The following sage advice comes from a recent LNVT Forum post from Wesley Eldred, ex-Little Bitt 37VT21, "I would encourage all owners to check this fitting as a failure when under way could be most inconvenient." 

Lady Katie's Failed Fitting

In 2013 Lady Katie 37VT28's fitting failed at the dock.  She slowly filled with water and was saved from completely sinking by an observant passerby. 
Corrosion on the Hose Fitting

Just last month Mike McCoy, Tug E. Bear 37VT62, found his fitting was badly corroded. 

Tug E Bear's New Bronze Fitting

He replaced it with a new bronze fitting and reported that the repair was straight forward and easy.  

Doing a simple fitting inspection during the Spring launch could prevent the trials and tribulations of an underway emergency.

Sunday, May 13, 2018

Sally W. 37VT42 in June Soundings

Hat tip to Peter Reich, Teddy Bear 37VT15, for letting us know about the article.  Double click on each of the article's pages to see a legible version.

Here's a link to some Soundings' LNVT videos:

Friday, May 11, 2018

Welcome Aboard!

A special welcome to new owners Mariah and Beau Hicks who just purchased 37VT05. Beau is no stranger to tugs as he works professionally on a tugboat in Fort Lauderdale. They currently are living in Richmond, VA with plans to move their new tug from Waterloo, NY to Urbanna, VA in late June/early July.

Mariah tells us:

"The past couple of years my husband, Beau, and I were living on a 41 Island Trader down in the Keys, specifically Marathon, FL.  We fell in love with the live aboard lifestyle!  Unfortunately, Hurricane Irma changed some things for us and our boat was not salvageable.  We temporarily moved to VA while we searched for our next home.  After living below the waterline we had decided our next boat would be a trawler.  Beau found a Lord Nelson on YachtWorld in November and we knew it was the boat for us.  Everything about her was perfect for what we were envisioning for our next home to cruise on.  This past weekend we just closed on hull 5 Carla B. in Waterloo, NY.   We are so excited to be joining the LNVT community!!  We have been following it now since November - reading the blog, the forums, the newsletters.  I was so enamored with the tugs that I actually painted Thistle 37VT47 in my last watercolor commission.  

While Carla B is a great name, we would like something that reflects us.  We will be renaming her to Miss. Willoughby.  Willoughby Spit (in Norfolk, VA) is where Beau grew up & where we met for the first time. My jeep was broken down on the side of the road and he was the one I flagged down to help me.  We started dating and got married a few years later in Willoughby Spit, so that town has a special place in our hearts.  The ultimate goal is to take the tug to the Florida Keys. "

Thursday, May 10, 2018

Tug spotting: C'est Si Bon

The Blessing of the Fleet and Opening Day Parade in Port Townsend, Washington included C'est Si Bon 37VT38 (owner Craig Kurath and proud pup

[Photo by the PTYC photo crew]

Monday, May 7, 2018

Tug Spotting: Lucy

Tug sighting:  Osprey Marina. Myrtle Beach SC

Peter S. Reich, MAC
⚓️ 631-749-0138 ⚓️

Tuesday, May 1, 2018

Resins: Isophthalic vs. Orthophthalic

Just below Nellie's bootstripe the hull has been sanded to reveal (starting in the pictures upper right and moving to the lower left) multiple layers of bottom paint (black and red), gel coat (bright white), barrier coat (gray), and fiberglass.

Tommy Chen said that he used two types of polyester resin (at least on the later tugs). Below the waterline he used an "iso" resin as it resists osmotic blistering.  Above the waterline he used "otho" resin.

"Orthophthalic polyester resin is the standard economic resin used by many people.  Isophthalic polyester resin is now becoming the preferred material in industries such as marine where its superior water resistance is desirable." From Net Composites.

To decrease the permeability below the water line iso resin was mixed with what Tommy called a "gray powder" and then applied to the hull with a roller.  I assume the gray powder contained plateletes, like those in Interlux 2000E, which make it more difficult for water molecules to pass through.  So effective is this gray layer of iso that Tommy says he made some tugs without gel coat bottoms.  Nellie D. #63 clearly has the gray layer between the gel coat and fiberglass.  According to Tommy, the bottom's gel coat should be about .7mm thick.

I measured a piece of Nellie's gel coat, which has the gray layer on it, at .027" or .6858mm.  The gray layer is very thin.

Dave Howell
Nellie D. 37VT63