Building Oars and Oarlocks

Having decided on Tulip Poplar for my oars, I drove down to Hearne hardwoods and found a straight plank 12' long x 2" thick.  I had them joint one edge.  I cut the two looms to 1 3/4" square and then used my jointer to make them eight sided.

Make the loops eight sided 

I marked off 10" by 1 1/8" diameter handles and then cut them out.

Cut out the handles

Make the handles eight sided

 I used a rasp, plane, chisel and sand paper to get everything mostly round.  As with most of my projects, I was able to justify the purchase of a new tool.  In this case it was a saw rasp from duckworks.

Round with a rasp and sand paper

I should have cut out the curved flats where the blades meet the looms before I rounded the looms - it would have been so much easier.  Ah well.  Then I glued on the blades.  I didn't have any marine plywood handy so I used AC Fir.  I put a fillet of thickened epoxy and embedded five or ten strands of linear fiberglass into the fillet.

Glue the blades

I tapered the loom with a drawknife and gave everything a coat of epoxy.  Then I put on three coats of spar varnish on the looms and a few coats of white rust-oleum enamel on the blades.

Taper the looms

Coat with epoxy, then varnish

10' 3" - that is a long oar

I made buttons (or stops) out of 1/4" nylon braid.  I tied a turks head as tight as I could get it but it was still loose enough to slide when subjected to a lot of force.  I varnished them in place - hopefully it will be good enough to keep them in place.

Turks Head Buttons

 After a trial row I found the oars needed counter weights.  I chose 1 3/4" propeller shaft zincs, each weighing 2.5 lbs each.  I think they are just right.

Couterweights

The cockpit coaming is about four or five inches inboard of where the oarlocks are normally mounted on a Core Sound 20 so I created outriggers out of ash and cherry.  The geometry isn't ideal - I have to sit on four or more inches of foam cushions to be comfortable.  

Outriggers for oar locks

Outriggers mounted on the coaming

Stowed under the coaming

Oars at the ready

Building two CLC Kayaks

the beauty of boatbuilding

After a lifetime of small sailboats, Julie and I are building two kayaks from Chesapeake Light Craft.  I'm still a sailor at heart, but Julie is probably more suited to kayaking. We can envision all sorts of fun combinations of sail + kayak.

I will build the Shearwater 16 and Julie will build a Chesapeake LT 16.  We bought the kits while at the Mid Atlantic Small Craft Festival and picked up kits a few weeks later from CLC's shop in Annapolis, MD.

The first  step was to augment my already extensive set of boatbuilding tools.  This included lots of different clamps from Harbor Freight Tools.  I also added to my workbench a few bench dogs manufactured by Record.  I inherited these beautiful cast iron devices from my grandfather.  They probably date from the fifties or sixties.

Record Bench Dog

 I also made a few light weight saw horses for assembling the panels.

light weight saw horse

Here's a view of panels being joined together.

Panel assembly

The temperature in my basement shop is in the low 50 degrees F so we are using work lamps with 70 Watt incandesent bulbs to get the surface temperature high enough to cure the epoxy.

heating lamps

The book case in the background has every issue of Small Boat Journal and most issues of Messing About in Boats.

the beauty of machine cut plywood kits

Tulip Poplar for Oars?

Our new Core Sound 20, Summer Breeze, needs a set of oars.   After researching various oar designs on the web and comparing the mechanical and subjective qualities of various woods, I've decided to make them out of Tulip Poplar which is cheap and plentiful here in south eastern Pennsylvania.  People are surprised when I tell them of my choice so I'm posting my analysis here.

Table 1 shows a few select woods that I wanted to compare.  Most of the mechanical properties are taken directly from the Wood Database, a fantastic resource for investigating boat building woods.

Table 1. Properties of woods for making oars

The table provides Density (how heavy the oars will be), Modulus of Rupture which denotes strength against bending force, Modulus of Elasticity which denotes bendyness, and price per board-foot.  FAS is code for furniture grade wood.

I want a wood that is light, strong and bendy.  It should look good but not cost too much.  Typical woods for oars and other spars include Sitka Spruce, Ash, Pine and Fir.  I am lucky to be 30 minutes drive from one of the best hardwood suppliers in the country, Hearne Hardwoods. The large yard is piled high with flitch cut logs air drying or waiting to be milled.

Flitch log at Hearne Hardwoods

They have great prices on Ash, Cherry, Pine, Tulip Poplar and lots of other exotics.  Most of the prices in Table 1 come from Hearne.  I've ranked my selection based on weight (density), elasticity, strength (modulus of rupture), quality (FAS, common, select, clear) and price:

• Sitka Spruce is very expensive ($15/BF Chesapeake Light Craft).  It has a good strength to weight ratio and is very elastic.  Too expensive around here.
• Eastern White Pine is the lightest in my list but also the weakest and most brittle (least elastic).  Hearne has some very clear white pine, but it is expensive.  
• Spanish Cedar is great to work with and beautiful to look at but it is brittle, a bit heavy and on the expensive side.
• White Ash is the strongest (modulus of rupture) and most elastic but also the heaviest.  Many great paddles and oars are made from White Ash and it is inexpensive but too heavy for my taste.
• I included Black Cherry just out of curiosity.  I think it might make fine oars.  It is more rot resistant than Ash but also less strong and elastic and costs more.  It is prettier, easier to work but not as tough.  There is a lot of locally grown cherry in PA so it is relatively cheap here.
• Western Hemlock (Hem-Fir) 2x stock from Lowes is cheap and has great mechanical properties.  Because it is only available around here as construction lumber (common grade), even the best planks will have some small knots.  
• Tulip Poplar has great mechanical properties, is fun to work with and looks good.  Hearne has great pricing on FAS grade (furniture grade) stock in many dimensions.

Grahame Byrnes of B&B Yacht Designs told me that Hem-fir is a great alternative to sitka spruce.  The wood database confirms this (Table 2).  Tulip Poplar appears to be another great alternative.  Robb White, a well known boat builder and writer used Tulip Poplar for many of his beautiful custom boats. Compared to hem-fir it is much prettier, easier to work with, just as light, about as strong and elastic and not much more expensive.

Table 2.  Hem-Fir and Tulip Poplar vs Sitka Spruce

Tulip Poplar is the wood for me.

Leeboard repair - the "rope trick"

Dry fitting for the "rope trick"

I damaged the leeboard on Cream Cheese last year by driving away from the launch ramp with the board dragging in the gravel.  I discovered my error after about 50 yards, but by that time I had chewed off about 3/4" inch off of the bottom corner of the leading edge.  Later on Grahame Byrnes, designer of the Core Sound series, told me about "the rope trick".  The idea is to glue an epoxy saturated synthetic rope (usually nylon) to the leading edge of the board, thus providing a well shaped but very durable surface.  Here's an example from the Core Sound 20, Dawn Patrol:

Rope on the rudder of the Core Sound 20, Dawn Patrol.
It protects the leading edge of underwater boards

I decided to try the rope trick myself.  First I cut away the damaged wood and fitted the rope.

Fitting the rope

Then I soaked the rope in epoxy and draped fiberglass cloth over it and let it partially cure (8 hours over a cool night).  I made a mistake at this point in the process.  I should have used thickened epoxy to fill the spaces between the rope and the board but I didn't.  As a result, there are air pockets.  Hopefully this won't be a major issue since the boat is dry sailed and all surfaces are thoroughly coated with epoxy.

Fiberglassing rope in place

Then I filled using epoxy thickened with fused silica and microballoons and let it cure.

Filling and smoothing

I made a first pass at sanding and smoothing and filled some more with thickened epoxy.

Final sanding before painting

A third reef for Cream Cheese? Wind Forces, Sail Math

I made the 96 sq ft mainsail for my AF3  from a Sailrite kit.  I gave them the dimensions and draft and asked them to put in two reefs even though only one is specified on the plans.  The second reef reduces the sail to about 49 sq ft.   Even with two reefs she is overpowered at anything above 25 mph.

Double reefed, 15 - 25 mph

No reefs, drifting along

An AF3 weighs 250 to 350 lb and has a 4' beam which is a bit narrower than other boats her size so her sail area has more of an impact on stability.  I am considering sewing a third row of reef points to get the sail down to 31 sq ft so that I can sail upwind more comfortably when the wind kicks up.

I don't want to spend a whole weekend sewing just to find out the boat won't point so I've done some searching on the web, some asking around (the watertribe forum was very helpful) and some calculating.

Will a third reef result in too little sail?
Adding a third reef will reduce sail from 96 sq ft to 31.5 sq ft.  Is that enough sail to make headway in 30 mph winds?  The force exerted by a sail is proportional to the square of the wind velocity.  Jim Michalak has given a simple formula:

 Max sail pressure (lbs/sq ft) = .0034 * V(kts)² * C

where V is in Knots and C is a constant representing sail efficiency from 1 to 2.  My mainsail has good draft and a nice shape, so I'm calling it a C=1.5.  Since I like to measure speeds in miles per hour, I applied an additional conversion and came up with the following table for my mainsail:

Force on sail (lbs) for different sail areas (sqf)
and wind conditions (mph).

Unreefed going upwind, AF3 likes a 10 to12 mph breeze the best.  This turns out to be about 42 to 62 lbs force exerted by the sail.  She sails upwind fine with two reefs in 20 mph = 87 lbs.  She is overpowered at 25 mph = 136 lbs.  A third reef at 31.5 sqft should generate 126 lbs at 30 mph.  Still managable and certainly not too little force.  So a third reef to 31.5 sq ft seems to be plenty enough to make headway.

Another possible issue is related to force of the wind on the hull.  As you reef down the sail, the force of the wind on the hull has a greater effect on the total force.

Wind force on exposed hull (frontal area) as wind increases. 

I admit that this computation is pretty loose: it assumes the hull acts like a very poor sail (C = .5) and the area exposed to the wind is about 3' x 8' (because the boat is presenting about 50% of itself to the wind).  The table predicts that at 30 mph, the wind exerts 32 lbs force on the hull.  At that same wind velocity, the triple reefed sail will exert 126 lbs force, so the math is still looking OK.

Will there be too much lee helm?
I am also concerned about lee helm, an unsafe situation in high winds. Without any reefs, the centroid of the sail is even with the trailing edge of the leeboard.  With two reefs in, the centroid is 13" farther forward (see picture below).  I would have expected to experience lee helm with the second reef in, but instead I get significant weather helm, especially during gusts above 25 mph.  I have no idea why this happens, but I can think of a couple of possibilities:

1. If you heel her over to port she wants to round up to starboard - just like steering a surf board.  Perhaps the turning forces due to the hull are a lot more powerful than the turning forces due to the sail center of effort..  
2. As you heel the boat, the center of effort moves to lee because the mast is angled over the water and the center of resistance (leeboard) moves to windward.  Perhaps the geometry of this situation lessens the imbalances in force (there is still a tendancy toward lee helm, but the force vectors are smaller).
3. An imbalanced rudder can make the problem more pronounced if the center of resistance of the rudder blade is too far behind the rudder pivot (thanks to SOS for that suggestion)

A third reef will move the centroid forward 19" (as opposed to 13" with two reefs).  So my tentative conclusion is - I'm hoping I'll get lucky and it won't cause lee helm.

Jim Michalak's articles on sail math:

• Sail Area Math
• Sail Sizing
• Sail Sizing 2

More upgrades

1. Reefing
In an attempt to make reefing go faster, I've made a few minor changes.

Snotter.  Up till now, I've simply tied the snotter around the mast.  There is a spring clip tied to the end of the boom which clips to the snotter.  This is a simple system, but it gets fouled with the sail lacing when raising and lowering the sail to reef.  The new arrangement uses a ring tied to the mast.  The spring clip is now clipped to the ring and tied to the snotter.

New snotter setup

Downhaul. I also got a larger hook for for my downhaul which is easier and faster to fasten.

Larger spring clip

I did a few reefing drill with the new rig in my driveway: the best I could do was about six minutes.  On the water, it will probably take closer to ten minutes.  The results are a bit disappointing, but I think the procedure will be safer and more reliable with the latest changes.

2. Oar Ports
Last trip we got a lot of water in the cockpit through the oar ports when it was blowing and choppy.  I made two covers for the oar ports to keep the waves out.

Panel Cart

I have a lot of lumber and sheet stock left over from old projects.  I usually find a use for it, but sometimes it takes five or ten years.  For a long time, I just stacked it against a wall in the garage, but it was difficult to find things, impossible gain access to keep the garage clean and mice and other animals would die back there.  Last year, I made a cart from particle board, 2x4's, galvanized pipe and 3" cast iron swivel casters.  It holds a ton of wood and is easy to move around the garage.

A few of the things in my cart:

• 4/4" pecky cypress planks from an old barn in Louisianna
• 1/4" UHMW polyethelyne sheet - slippery, dense, machineable.  Great for rub rails and bearing surfaces
• 1/2" MDO plywood (paper glued on one side)
• 3/4" ash and cherry
• 1/4" plexiglass

Boat building glue - 12 year test

When I built Cream Cheese in 2000, I experimented with four different glues.  I figured that about 10 years into the future I would have some useful information to share.  Now that over a decade has elapsed, I feel I can report on the success rate.  I've had the boat in a garage for about half of the time and under polytarps for the other half.  Best to worst:

1. Epoxy thickened with fused silica. I use thickened epoxy from Raka for the mast, leeboard, rudder, butt-blocks on the hull and some of the deck cleats.  Most of the epoxy joints have held up.  The leeboard, which probably gets the most abuse of all the parts on the boat, has had some delamination.
2. PL Premium. I glued the port chine log and both gunnle's with PL Premium and it hasn't required any repairs yet, but I suspect it may need some minor work in the near future.
3. Elmers liquid polyurethane.   I used this liquid glue for gluing the 3/4" pine frames to the bulkheads.  Some of these joints have required repairs.
4. PL 500.  I used this for the starboard chine log and I've had to repair practically the whole length.  Luckily I didn't use it for anything else

This year I am fixing some of the few remaining spots that haven't been repaired on the starboard chine. To make the repair, I use a chisel and razor to cut out the old glue and create a channel.  Then sand the surrounding area.  Finally, I wet out the joint with epoxy and then apply a fillet. 

You can see there is a gap between the
chine log and the hull.  Fore and aft are fillets
from where I've fixed other parts of the joint. 

For this type of job, I have a number of sanding tools in my box: A Bosch mini belt sander (6"x1.5"), a Dremel combination cutter/sander, a Bosch 2.3 Amp random orbital sander and a Resp-O-Rator.

Sanding Tools

Fillet thickened with fused silica and microballoons

A Sharpie in Core Sound - Part 1 Preparation

go to Part 2

go to Part 3

go to Part 4

In March, our kids were scheduled to go on a week long service trip.  Julie and I haven't been on an extended vacation on our own in a very long time, so we planned to go camping or dinghy cruising somewhere in the south, weather depending.  In preparation, I started making long awaited improvements to Cream Cheese.  The short list included:

• cabin floorboard for sleeping aboard
• on-deck cargo rails for lashing spars
• cockpit thwarts for more comfort
• tiller hiking stick
• second bower anchor
• motor mount and motor 
• camping tent
• new mainsheet arrangement

Floorboards

In past cruises, we have always brought tents and camped ashore but this trip I wanted to try sleeping aboard.  Because of the steep rocker of the hull, floorboards are necessary to keep your head above your feet.  There is 7' clearance from cockpit bulkhead to the stem, but the main obstacle to sleeping two people in comfort is the mast.  When sleeping aboard, we stow the mast on deck (on the spar rails) and move all of the cargo to the cockpit.  This leaves a comfy cabin about the size of a backpacker's tent. For floorboard material, I used old 7/8" boards that came from my sister's 90 year old house in Philadelphia.  They are probably old growth yellow pine, but they may be fir.  The hardest part was stripping off the thick layers of old paint.  The floorboards are finished with three or four coats of Watco Teak Oil.

Note the plug over the
mast step.  No bumps
when  sleeping!

Spar Rails
I've always kept the oars lashed to cargo rails in the cabin, but for extending camping, the cabin is full of gear so the oars need to be stowed outside.  Norm Wolfe stores his oars on deck on his Michalak Normsboat.  I mounted unfinished ash strips with 3/8" holes to the deck using silicon bronze screws and 3M 5200 adhesive sealant.

Mast, boom and oars on deck

Thwarts

For 12 years, we've sailed Cream Cheese without any seating per Jim Michalak's plans.  For the first few trips I had cockpit benches port and starboard, but they were too high and in the way of practically anything you would want to do so I removed them.  We would sit on life jackets and I used a small cooler as a rowing seat.  For this trip, we would be spending lots of time in the cockpit and it would be pants and jacket weather and so I added transverse thwarts.  The forward thwart is set down low so that it is in the optimal rowing position.  The wood is from the same 90 year old cabinets as the floorboards, finished with Watco Teak Oil.  I spaced out six 3/8 holes near the thwart edges for lashing cargo and for the new mainsheet combination block/cleat.  Both thwarts work great with the bimini too.  

   

Second anchor
My primary anchor is an aluminum fortress Danforth style with six feet of chain and 150' of 3/8" nylon rode.  In any kind of wind, Cream Cheese sails around at anchor like a chihuahua on a leash.  I've wanted a second anchor for quite a while so I added a 4.4 lb Lewmar claw anchor with 15' of chain and 200' of 3/8" nylon rode.

Second bower (left) and best bower (right)

Cargo carabiners
I've always had cargo rails in the cabin, but lashing things to them involved tedious lacing of lines.  Hanging aluminum carabiners made stowing cargo much easier.

Tiller stowed on port side in dufjel ready for the highway

Motor and motor mount

Till now I've avoided a motor for Cream Cheese, but for this trip, I opted to pollute my transom with a motor mount.  It was only used twice, but both times it was a nice convenience.  I still I had to beef up the transom, since the boat is not designed for a motor.  Because the AF3 is so light, has so much hull rocker and has such a narrow transom a motor just isn't a good fit.  The weight of a motor that far aft can really pull the stern down.  For cruising however, we would have lots of cargo in the cuddy to counter balance the motor.  Even so, I chose a Suzuki 2.5 because at 30 lbs it is the lightest water cooled four stroke engine that you can get.  I decided against a Honda 2 (27 lbs) because it is air cooled which makes it quite noisy.  I bought an adapter plate so that I can remove the motor mount when I don't want a motor. 

The motor mount slides
into an adapter plate
so that it is easily
removable.

Tiller extension
I've had a home made tiller extension, and was reluctant to shell out the money required for a manufactured one when I could build my own.  I had one on my Drascombe longboat and loved it.  This one from Forespar was one of the best $80 I've ever spent.  The instant length adjustment and quick release install/removal are key and hard to replicate in wood.

Tiller extension, old mainsheet arrangement.

Camping tent
I intended to sew a good camping tent out of the same sunbrella acrylic fabric that I used for my bimini , but I ran out of time and made a "pattern" tent out of heavy duty gray polytarp.  In retrospect, this was a good idea because I was able to see the design in many conditions including heavy rain and 20 to 30 mph winds and can now make a real one from that knowledge.

Mainsheet

Before

After

The plans for AF3 show the mainsheet led aft to the tiller.  This had two problems.

1. You don't get any mechanical advantage.  When you are heading upwind in 20 mph, even with a double reef, your hands will get sore.
2. There is no convenient way to have one hand on the tiller and one on the mainsheet.  This is crucial in gusty conditions.

The new scheme works great.  I laced a single block about 1.5 feet from the end of the boom and run the main sheet from the rudder post through that block down to a racelite block/cleat combination (from the great folks at Duckworks) that is laced  to the forward thwart.

This gives me a 2:1 mechanical advantage and makes it easy to sail with one hand on the tiller and the other on the sheet.

Racelite Block/Cleat Combination

In a separate post, I'll describe how all of these changes worked out during our trip to the Core Sound of North Carolina's outer banks.

go to Part 2

go to Part 3

go to Part 4