Saturday, June 22, 2013

Introduction

Mo 'Poxy's Boat Building Project
Nemah
a Plywood Stitch and Glue Sharpie



Introduction


It has been a decade since I built my last boat.
It is 2013 and I have the itch again so I have started building another boat.
If I count correctly, this is the 8th boat that I have built.

Let's count....
1) Tracy O'Brien's Headwater 14 -1998
2) Tracy O'Brien's V20 - 1993-1994
3) A self-designed scow for hauling lumber to a boat-only-access cabin construction site -1998
4) Chesapeake Light Craft: Chesapeake 18 Kayak - 2000
5) Chesapeake Light Craft: Chesapeake 18 Kayak - 2000 (another)
6) Chesapeake Light Craft: Chesapeake 17 Kayak - 2000
7) Chesapeake Light Craft: Chesapeake 14 - 2000
8) and now I am building Tracy O'Brien's Nemah- 2013

The Nemah is a sharpie, made of plywood using the stitch and glue construction technique.
It can be sailed or rowed.

I am building her for rowing, using a foward-facing rowing system.

This website contains photos and descriptions of the project.


TIP: START COLLECTING DISPOSABLE CONTAINERS LONG BEFORE STARTING AN EPOXY PROJECT. THE CONTAINERS WILL BE USED FOR MIXING EPOXY SO THE CONTAINERS SHOULD BE SMOOTH WITH FEW SURFACE DIMPLES AND CREASES. TIN CANS ARE NOT VERY GOOD SINCE THEY HAVE THOSE WRINKLES IN THEIR WALLS WHERE UNMIXED EPOXY CAN HIDE. PLASTIC COTTAGE CHEESE CONTAINERS ARE GOOD BECAUSE THE WALLS AND BOTTOM ARE FLAT AND UNMIXED EPOXY CANNOT HIDE. YOU WILL NEED A GAZILLION DISPOSABLE CONTAINERS TO BUILD A PLYWOOD/EPOXY STITCH AND GLUE BOAT. MY MOTHER TOLD ME A GAZILLION TIMES NOT TO EXAGGERATE.

Thursday, June 20, 2013

Preparation

Plans

I bought boat plans from Tracy O'Brien. 156 Bunker Creek Road Chehalis, WA 98532 United States. Tracy O'Brien's plans and instructions are always very complete. All pieces are shown with complete dimensions. They all fit together just as designed. There is no "Beat to fit. Paint to match" required.

O'Brien plans for the Nemah


Scarphing

The project begins by joining 8-foot sheets of plywood into longer sheets. The sheets are joined by scarphing and gluing, to form sheets 16 feet long. 

I used a John Henry scarphing jig attached to my Makita 4-3/8-inch power planer. This scarphing jig is available from John Henry Inc. POBox 7473, Spanish Fort, Alabama, 36577 (251)626-2288.


Makita power planer with John Henry jig


Underside of jig

Scarphed panels are then glued together with epoxy, to form long sheets.


Scarph-cut plywood

Joining panels at scarph joints

TIP: A COMMON MISTAKE WITH EPOXY IS STARVING THE JOINT. IF YOU HAVE A PERFECT JOINT AND YOU CLAMP TOO HARD, YOU CAN SQUEEZE THE EPOXY OUT OF THE JOINT AND REDUCE THE INTEGRITY OF THE JOINT. UNLIKE WOOD GLUE, JOINTS THAT DON'T FIT-UP PERFECT AND HAVE A LITTLE EXCESS EPOXY IN THEM ARE STRONGER THAN STARVED JOINTS. REMEMBER, THE EPOXY IS WAY STRONGER THAN THE WOOD.



A quality scarph joint is hard to see, even in this cheap CDX plywood.



Cutting, coating and sanding

After creating the long plywood panels by scarphing, it is time to cut the bottom and side panels to the proper shape. The plans provide a table of offsets for each shape. The offset points in the tables are marked on the bottom and side panels.

Laying out stations and offsets on plywood

A smooth curve is drawn to connect the offset points. I used a long supple batten strip to trace the smooth curves.

Using a supple batten to connect the dots in a smooth curve



Then I cut to the line with a jig saw.


Cutting panels to shapes shown in the plans



After cutting the panels to shape, each panel is coated with epoxy-impregnated fiberglass. I use a window washing squeegee to spread the epoxy.





Notice that I did not epoxy the outer 2 inches of fiberglass to the panels. That is where the biaxial fiberglass tape will attach in the future "glue" step.

I purchased my fiberglass from Jamestown Distributors

And I used West System 105 Epoxy Resin and 207 Hardener

TIP: MY 2 FAVORITE EPOXY COMPANIES ARE WEST SYSTEM AND SYSTEM 3. THEY BOTH HAVE GREAT BROCHURES ON WORKING WITH EPOXY. HERE ARE A FEW TIPS ON WORKING WITH EPOXY.

1) MIX SMALL BATCHES OF EPOXY UNTIL YOU LEARN THE APPROPRIATE BATCH SIZE. LARGE BATCHES MAY LEAD TO WASTED EPOXY, WHICH IS QUITE EXPENSIVE. AND, LARGE BATCHES MAY "KICK OFF" CURING IN THE POT BEFORE BEING USED, WHICH CAN BE A DISASTER.

2) IF YOU SPREAD MIXED EPOXY THIN, IT WILL HAVE A LONGER POT LIFE SINCE IT WILL NOT HEAT UP. IF YOU LEAVE IT IN THE POT, IT WILL GET HOT AND CURE TOO FAST.

3) THIN FIBERGLASS CAN BE LAYED UP "DRY" (PLACED ON DRY WOOD THEN SATURATED WITH MIXED EPOXY). THICK FIBERGLASS LIKE BIAXIAL TAPE MUST BE SATURATED BEFORE LAYING UP. WHEN LAYING F/G FABRIC, BE SURE THAT THE F/G DOESN'T FLOAT IN THE MIXED EPOXY AND SEPARATE AWAY FROM THE WOOD SURFACE. IF IT FLOATS, THE STRUCTURAL INTEGRITY IS STILL GOOD AND THE FINISH IS STILL BRIGHT BUT THE BUMPY IRREGULAR SURFACE WILL DRIVE YOU NUTS.

4) USE PUMPS THAT DISPENSE THE PROPER PRE-MEASURED RATIO OF EPOXY AND HARDENER.

5) WHEN WORKING WITH EPOXY, EVERYTHING SHOULD BE DISPOSABLE. YOUR GLOVES, BRUSHES, MIXING POTS, STIR STICKS, ROLLERS, SPATULAS, SQUEEGEES, SHIRT, PANTS AND HAT WILL GET EPOXY ON THEM. CLEANING EPOXY REQUIRES SOLVENTS THAT ARE CARCINOGENIC. IT IS YOUR CHOICE, CANCER OR DISPOSABLE.

6) ABOUT BLUSHING: NEAR THE END OF EPOXY'S CURING, A REACTION WITH OXYGEN CREATES A WAX ON THE SURFACE AND A WEE BIT INTO THE SURFACE OF THE CURED EPOXY. THIS IS CALLED "BLUSHING". FUTURE EPOXY AND PAINT WILL NOT STICK TO THE WAX. REMOVAL OF THE WAX REQUIRES WASHING WITH WATER THEN SANDING. WHEN MORE EPOXY MUST BE APPLIED TO A PREVIOUS EPOXY LAYER, SUCH AS ADDITIONAL COATS OR GLUING TO A COATED SURFACE, APPLY THE NEXT EPOXY LAYER/GLUED ITEM BEFORE THE PREVIOUS LAYER CURES. THAT WAY, YOU WON'T HAVE TO SAND ANY WAX AWAY AND YOU WILL GET A CHEMICAL BOND BETWEEN THE LAYERS WHICH IS WAY STRONGER THAN THE MECHANICAL BOND THAT RESULTS FROM SANDING. OR, USE A NON-BLUSHING HARDENER LIKE WEST SYSTEM 207 HARDENER. 

Once the epoxy has cured, I sand away the excess fiberglass.
   


Although the plans say to sand the entire panels, since my final finish will be bright uncoated epoxy, I did not sand the entire panels. This starts the discussion about UV exposure. This boat is an experiment. My hypothesis is that, here in Alaska (where even on the sunniest days this boat will see little sun and in the winter there is no sun) UV exposure is not an issue. I'll let you know the result of the experiment in 20 years.

I did not apply fiberglass/epoxy to the 2 inches around the outside edge. This is where the biaxial tape will be applied to stem, chines and transom joints during the future "glue" phase of the stitch and glue boat building. I sand only the areas where there will be future epoxy such as the stem, chines and riblet locations.

Riblet locations sanded
TIP: POWER SANDING AND POWER CUTTING CREATE LOTS OF DUST THAT CAN MAKE A MESS OF YOUR SHOP AND CREATE PROBLEMS FOR EPOXY, PAINTS, VARNISHES AND MARRIAGES. I DO ALL OF MY POWER SANDING, TABLE SAW CUTTING AND CIRCULAR SAW CUTTING OUTSIDE.

TIP: MY RANDOM ORBITAL SANDER IS GOOD FOR REMOVING LOTS OF MATERIAL IN A WELL-CONTROLLED MANNER. BUT IT LEAVES THEM LITTLE SWIRLIES EVERYWHERE. THOSE SWIRLIES HAVE A WAY OF SHOWING THROUGH PRIMERS, PAINTS AND VARNISHES. FOR SURFACES THAT WILL BE VISIBLE IN THE FINAL BOAT, I ALWAYS FOLLOW RANDOM ORBITAL SANDING WITH A PALM SANDER TO REMOVE THE SWIRLIES. 







Saturday, June 15, 2013

Stitchin' and Gluin'


Stitching

Stitch the panels together and get your first look at the boat's shape.

Stitch the stem first


Coat the wires with floor wax (so they can be easily pulled after the epoxy cures) and stitch 'er up!

Then install and stitch the bottom panel

Until, now, this project has been progressing fast - working with big slabs of plywood, laying large sheets of fiberglass, spreading cups of epoxy and quick cutting. Stitching is the first slow hand work and it takes patience. Calm be Luke Skywalker.

Stitching the chine


Stitching the transom

CAUTION: THE ENDS OF THE CUT WIRES ARE RAZOR SHARP. LEATHER GLOVES WILL HELP IF THEY PROVIDE THE NEEDED DEXTERITY. THINK ABOUT AND EXPERIMENT WITH YOUR HAND MOTIONS. CONSIDER WHETHER TO PROGRESS FROM LEFT TO RIGHT OR RIGHT TO LEFT ALONG THE BOAT. THIS WILL SAVE A LOT OF BLOOD. KEEP BAND AIDS AND MEDICAL TAPE HANDY.

What was yesterday a bunch of flat panels, is today a 3D boat!!!




Turn the boat over and install the spreaders. The locations and lengths of the spreaders are specified in the plans. Then tighten the stitches to get the final hull shape.





TIP: AFTER TIGHTENING THE STITCHES, BEND THOSE SHARP LITTLE BUGGERS SO THAT THEY WON'T JUMP OUT AND CUT YOU.  



Gluing


Time to start working on the inside of the boat. I was waiting on my clear epoxy hardener to arrive so I did things a little out of order by installing the riblets before taping the interior.

Riblets clamped for gluing

To tape the interior, pre-coat the fillet and tape area with un-thickened epoxy/hardener for a good bond to the wood. Then fillet the stitched joints with a mixture of epoxy, hardener, silica and wood flour that looks like peanut butter but doesn't taste as good.

Fillet in the chine
Then tape the fillets, with biaxial fiberglass tape, saturated with epoxy/hardener. If you wait until the fillet cures, you have to painstakingly sand it. Otherwise, tape over the soft un-cured fillet and save the sanding for later.



Cut the tape longer than needed. Where it sticks out past the boat you can try to cut the excess off before the epoxy cures and make a mess. Or, let the epoxy cure and cut the excess away in the dry.

Fillet and tape completed

After the epoxy/tape cures, I take a Surform and knock off the bumps in the tape/epoxy. Then I apply one or two coats of unthickened epoxy to the tape. 




TIP: SURFORMS ARE GREAT FOR KNOCKING OFF THE HIGH SPOTS OF EPOXY BUT THEY TEND TO CAUSE COLLATERAL DAMAGE TO SURROUNDING AREAS. WITH EPOXY THIS IS OK SINCE WHEN RECOATING THE AREA, A DAB OF EPOXY WILL REPAIR THE DAMAGE. HOWEVER, THIS IS NOT SO WITH UNCOATED WOOD. DON'T USE SURFORMS AROUND UNCOATED WOOD OR YOU WILL BE SANDING THE DAMAGE OUT OF THE SURROUNDING WOOD.







Monday, June 10, 2013

Whales, Rails and Bottom


Inwhales and Rubrails

After the interior joints are complete, the inwhales can be installed.



I originally desired to build this boat with no metal fasteners. But, working by myself, I found that when it came to clamping 14-foot long inwhales with thickened epoxy applied, there was no way I could get the inwhales in their precise location and it would be an epoxy mess. So, I adopted this process:

1) Cut and prep the inwhale to final dimensions, except the top surface. The top surface will be sanded later.

2) Clamp the dry inwhale in-place, exactly where I want it.

3) Install stainless steel screws as needed to mount the inwhale. I installed the screws from the outside, through the side panel and riblets, into the inwhale. I countersunk the screws in the side panel since the rubrail will be glued to the outside of the side panel over the screws. (See the TIP below)

4) Remove the clamps.

5) Remove the screws.

6) Coat the gluing surfaces with un-thickened epoxy.

7) Butter the side panel and riblets with thickened epoxy for gluing the inwhale.

8) Use the screws to install the inwhale so it is both screwed and glued.

9) Use clamps as needed to get a little thickened epoxy to squeeze out between the side panel and the inwhale where there are no screws.

10) Remove excess thickened gluing epoxy before it cures.

 The exterior stem and transom joints can be rounded and taped.





The rubrails can be installed.




To screw and glue 16-foot rubrails, I:

1) Prep the outer and bottom faces to final conditions but I left the rubrails long, to be cut and sanded to their final length after the gluing epoxy cures.

2) Clamp the dry rubrail in-place, exactly where I want it.

3) Install stainless steel screws as needed to mount the rubrail. I installed the screws from the outside, through the rubrail and side panel, into the riblets or inwhale. I countersunk the screws in the rubrail for plugging.

TIP: IT IS AT THIS POINT WHERE I REALIZED THAT THE INWHALE SCREWS ARE IN THE WAY OF THE RUBRAIL SCREWS. NOTE TO SELF: NEXT TIME, INSTALL THE INWHALE SCREWS LOWER AND THE RUBRAIL SCREWS HIGHER SO THEY DO NOT INTERFERE WITH EACH OTHER.
4) Remove the clamps.

5) Remove the screws.

6) Coat the gluing surfaces with unthickened epoxy.

7) Prepare some thickened epoxy for gluing. Don't prepare the whole batch, just enough for a few feet of rubrail.

8) Butter 3 feet of the side panel gluing surface with thickened epoxy for gluing the rubrail. Don't butter over the screw holes, you will need to know where they are located.

9) Use the screws to mount about 2 feet of rubrail.

10) Use clamps as needed to get a little thickened epoxy to squeeze out between the side panel and the 2 feet of screwed rubrail.

11) Scrape off the squeezed-out thickened epoxy and use the scraped-off thickened epoxy to butter another 2-feet of the side panel.

12) Repeat steps 9 through 11 as needed to mount the entire rubrail, adding a little bit of new thickened epoxy when needed.

13) Use the extra thickened epoxy to plug the screw holes and cover the screw heads. Let the plug epoxy stick out a little beyond the rubrail surface.

14) After the epoxy has cured, remove the clamps and cut the rubrail ends a hair long of their final length. Sand them to their final length.

15) Sand the epoxy screw head plugs flush with the rubrail. 

Bottom Work

Turn the boat over and pull the stitches. Use diagonal snips to snip the stitches where the stitches' path through the epoxy will be straightest. Use vise grips to grab the stitches and pry against a piece of scrap wood.


Note the Lady C in the background. Built her over 20 years ago. Another Tracy O'Brien stitch and glue design.

Sand the chines round for taping. 







Fiberglass the bottom

Dry lay up of the bottom fiberglass fabric 

Install  biaxial fiberglass tape to the chines.



In the above picture, note the hole through the stem. The hole does not allow water in because of the glob of epoxy, sawdust and fiberglass inside the stem. This glob is where excess epoxy goes during other parts of the work.

I installed a steel bow eye on the Lady C. On her maiden voyage, as I pulled away from the float on a windy day, the bow swung over the float and I heard a strange snap. When we spun around far enough, I could see that my bow eye had hooked on a float cleat and broke clear off. The bow eye was hanging on the cleat. I couldn't do that again in a million tries.

On the next trip I saw the Blue Heron moored in Little Jakolof Bay with a hole through her stem rather than a bow eye. Six of my boats now have holes through their stems and no bow eyes.


Install the skeg



The wet-out of the bottom fiberglass fabric, biaxial taping of the chines and gluing of the skeg were all done in one grueling 5 hour session so that no epoxy curing occured between layers. The bottom fiberglass cloth and chine tape are epoxied directly to the dry plywood and the fabric and tape have a chemical bond wherever they overlap. The skeg has a chemical bond to the bottom fabric.

Finish the bottom by removing the excess fiberglass. The sharp egdes of fiberglass are smoothed and the chines get a final coat of epoxy and the bottom is complete.














Wednesday, June 5, 2013

Wheels and Oars


Launch Wheels

I reinforced the transom for mounting of the launch wheels.



Then I installed the launch wheels.



Forward-Facing Rowing System


I purchased a forward-facing rowing system with spoon-blade oars from Gig Harbor Boats.

Here is  a sequence of pics to show how the FFRS works...
Handle and paddle full foreward

Handle and paddle at mid-sweep

Handle and paddle near the end of stroke

Handle and paddle at end of stroke


Mount the forward facing rowing system on the Nemah hull.

Mechanical contraption in-place

Handles and paddles installed

System stowed in boat

Time for a test ride!









Saturday, June 1, 2013

Test Ride and Retrofit


Test Ride


Load her on the snowmachine trailer




Haul down the beach







I have not built the rowing thwart since I don't know where or how high to make it.

I'll take along a cooler and some blocks to experiment with the location of the thwart.



Her we go...




The test launching taught me that the Nemah is too big for the forward facing rowing system. The FFRS has an effective oar length of 6½ to 7 feet. The Nemah is a big boat that needs a strong oarsman with 8-foot oars. I decided to forego the FFRS and build the Neamh as a traditional rower, convertible between one and two oarsman.




Dual oarsmen setup

Single oarsman setup

Then I sold her and built the Sea Scull