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Showing posts with label Hull&Topsides. Show all posts
Showing posts with label Hull&Topsides. Show all posts

Sunday, August 10, 2014

Bottom Work


The Haul Out













Removing the old ablative bottom paint

This may sound crazy but it worked out very well and made the job much easier.   I starting off making little but steady progress sanding off the old bottom paint with a combination of 40 and 80 grit sandpaper using an orbital Dewalt sander.  This is a messy, toxic, and muscle aching process.

I found that scraping off the old bottom paint went much faster. The paint came off in chips which fell nicely onto a tarp for easy clean up.  The key is using a good scraper.  I used a Bahco scraper with a long lasting sharp carbide blade.  I even purchased a replacement blade but never needed to replace the original blade.   Yes, one blade scraped the whole hull and it was still sharp.   But more important than needing to replace blades is that a good sharp carbide scraper will remove the bottom paint without gouging the underlying surface.  After scraping, a light sanding with 80 grit and it was done.

Below are pictures illustrating the process.


jack stand patch showing old bottom paint

Bahco carbide scraper
jack stand patch during scraping with Bahco scraper,
after scraping and a lite sanding, the area looks like surrounding 

Keel Fairing

Standard for C&C, the Landfall 38 comes from the factory with an external lead keel bolted through a solid fiberglassed keel stub.  Most C&C sailboat exhibit a mostly cosmetic crack along the keel/hull joint.   This is commonly referred to as the C&C smile.  There are many solutions to deal with the C&C smile, typically ranging from yearly caulking and painting to more long term elaborate fiberglass wrapping.   At some point prior, the Johanna Rose had her whole keel fiberglassed over.  Unfortunately, the fairing which was used over the whole keel was a polyester based as it (and only the fairing) was full of blisters.  From my inspection, it appeared that the work was done using epoxy resin and fiberglass, but for easy sanding, polyester fairing was used over the fiberglass.  It may have seemed reasonable at the time, or unwisely justified since a barrier coat was applied over the fairing.

The fairing was removed down to the fiberglass on the keel.  The fiberglass was in great shape with absolutely no blistering issues.  A gallon of East System epoxy with hardener was purchased  along with a gallon of colloidal silica and a gallon of 3M glass spheres from Noah's Marine Supply.   First the exposed fiberglass was wetted with epoxy then faired over that with thickened epoxy using a mixture of 50-50 colloidal silica to the 3M glass spheres.   As most know,  sanding epoxy is a like sanding a rock.   Thickening with 3M glass spheres, makes sanding the fairing much easier, but on vertical surfaces you need to add colloidal silica to the mix otherwise the fairing runs and sags.  Te West System pumps were used to meter the epoxy (5:1) which greatly aided in making many batches.   Once cured, the fairing was sanded with 80 grit using an orbital sander.


Barrier Coat

After performing all hull and keel fiberglass, epoxy fairing, and sanding work, an Interlux Interprotect 2000E barrier coat was applied.   As recommended by the manufacture, 5 coats of Interprotect 2000E was applied in alternating colors of grey and white.    The barrier coats went on without much issue.  For the current temperature, each coat required at least 2 hours of drying time before overcoating with additional barrier coat.   The last barrier coat required special attention and planning as you needed to apply the bottom paint within a time window(there is a finger print test).  In my case, about an hour after applying the last barrier coat,  I was applying the bottom ablative paint.  Since it took about an hour to apply the last barrier coat, I basically went from barrier painting to bottom painting.

hull prior to barrier coating
first application of Interprotect 2000E


flush mounted thru-hulls

four coats of Interprotect 2000E ready for the fifth coat followed  by bottom paint


strut with cutlass bearing and shaft removed




Ablative Antifouling Bottom

Pettit Ultima SR-60 Antifouling Paint was used on my C&C 29, and after several years in the water, the bottom was still looking great.  The only problem occurred with the bottom 6" of the keel which was due to the keel sitting in soft silt during the winter low tides.  A good stiff brushing did clean this area up and exposed fresh antifouling paint.  The rest of the hull would get a little slimy which would be remove with a dive mask every few months wiping with a microfiber wash glove.    Based on the good previous results,  Pettit Ultima SR-60 was chosen for the antifouling bottom paint.   This stuff is a bit expensive, but too often I see people pay half as much for bottom paint but then need to paint 3 times as often.  





bottom painting
bottom painting 


a look from astern






bottom with rudder installed and painted

 propeller, shaft, and new cutlass bearing


 Bottom Paint Performance

I hauled the vessel out at the end of 2017 so that I could install a new refrigeration system which required replacing the galley sink thru-hull and seacock with integrated thru-hull heat exchanger.

Monday, June 2, 2014

New Thru-hulls and Seacocks


Old Thru-hulls & Seacocks

When I purchased the Johanna Rose, I had to transport this engineless vessel over 130 NM home to my marina.   I did not dare touch any of these seacocks for fear of disaster.  once hauled out of the water, I was glad to first remove the old thru-hulls, decaying seacocks, and cheap hose which were used for under the waterline scupper drains(see photos).

A concern with with any cored hull boat is water intruding into the core and leading ultimately to delamination.   The Johanna Rose exhibited no signs of wet core as she tapped out solid all around, had no signs of blistering (other than over the lead keel, see post on bottom work), and did not weep during the many months on the the hard.  But the first real concern and test was in removing the old thru-hulls.   Old leaky thru-hulls have been know to cause wet core problems.  On the LF38, which is cored with end grained balsa ever where except for regions where thru-hulls are located.   In this area the core is marine grade plywood.   the Johanna Rose has 8 under water thru-hulls: 2 in the galley, 3 in the head, and 3 in the engine well.  I removed all thru-hulls with a tool I borrowed from the marina.   Upon inspection of the inner core, I found no wetness or indications that thru-hulls were leaking.  This was a great news.  


removing old thru-hull


a close up view of the engine water intake seacock
& port scupper seacock

old seacocks in the engine well, notice the quality hose 




NEW Thru-hulls & Seacocks
  • thru-hulls  
    • (2)    3/4”    Groco FTH-750 
    • (1)    3/4”    Groco TH-750 
    • (3)    1-1/2” Groco FTH-1500
    • (2)    3/4"     Groco THXL-750-W  
  • seacocks 
    • (5)     3/4”     Groco FBV-750 
    • (3)     1-1/2”  Groco FBV-1500





Reaming Back the Core and Filling with Thickened Epoxy

The plywood core was reamed back from the thru-hull hole using a Dremel and a sanding drum following the procedure illustrated by Wally Bryant on the Stella Blue site.  The seacock boltholes were over drilled to expose clean fiberglass.  A coat of Johnson Paste Wax was applied to a thru-hull so that a thru-hull inserted into curing epoxy would release easily.  These thru-hulls were inserted with thickened epoxy to fill the inner reamed out area and a proper faired flush mount fit.  The reamed out area and the boltholes were first wetted with epoxy before being generously filled with epoxy thickened with colloidal silica.  


thru-hull in galley near keel stub
























The Installation

The seacocks are mounted to backing plates made from a 1/2" sheet of structural fiberglass (FRP).  These FRP mounting plates are first aligned using a tightened thru-hull, marked, and then epoxied to the hull after grinding a clean surface.   The hull and backing plates are first coated with wet epoxy and then coated with epoxy thicken with colloidal silica  and finishing with a fillet of thickened epoxy along the backing plate circumference.  Care was taken so that epoxy would not interfere with the seacocks threads, but just to get certain, a tightened waxed thru-hull remained in place while the epoxy cured.     Prior to final installation, the thru-hulls were removed, soaked in Naphtha to dissolve the wax.   With the seacocks firmly epoxied to the hull, the thru-hulls were installed using plenty of adhesive/sealant.  after which the area is cleaned, sanded, and lightly faired with thickened epoxy.


  Seacocks
engine well seacocks 

new seacocks in the head

new seacocks under the galley sink







Thru-hulls
port scupper thru-hull and engine intake thru-hull 

starboard scupper thru-hull

head thru-hulls


head thru-hulls after first barrier coat