Trailering Your Oar Cruiser

Jim Michalak’s essay on trailering … very thorough… a ‘must-read’ article if you are going to trailer your boat.  Just one of the illustrations in this article that solves a problem: How to support a flat bottom boat on the trailer.

Jim Michalak Suggestion to Use a Plywood Base to Support the Hull

Chuck Leinweber's (Duckworks Magazine and Boat Builder’s Supply) article on using a  Harbor Freight Trailer to carry his "Ladybug" and a follow-up article on his modifications to the Harbor Freight trailer. For example, he added a tongue and a third wheel, like this:

An Added Tongue and Third Wheel to a Harbor Freight Trailer

Shorty Routh (of PDR fame) wrote this article on his modifications to Harbor Freight trailers, such as this one:

Shorty Routh's Wood Post

For my own Lillistone Flint (14' 7", 125 pounds) I use a light weight "Load Rite" trailer similar to this one. I've been very happy with it.

Light Weight Load Rite Trailer with 1000 Pound Capacity

A safety check list for trailering that was in multiple sites I visited for this post:

• Coupler, hitch and hitch ball are of the same size
• Coupler and safety chains are safely secured to the hitch of the tow vehicle
• All fasteners are properly tightened
• Boat is securely tied down to trailer (winch line is not a tie down)
• Wheel lug nuts are properly tightened
• Wheel bearings are properly adjusted and maintained
• Load is within maximum load carrying capacity
• Tires are properly inflated
• All trailer lighting is working properly
• Trailer brakes are properly adjusted and working (if trailer is so equipped)
• Brakes and additional equipment meet all local and state requirements

Selway-Fisher’s Mandarin 15’ & 17’

Selway-Fisher has a large collection boat plans, including many rowing designs.  One of the designs is the Mandarin, in both a 15’ (4.6m) and 17’ (5.2m) version. The versions are virtually identical except for length and interior arrangement of seats and oar locks.

Specifications for 15' and 17' Mandarin

Mandarin 15'

• Length: 15' (4.6 m)
• Beam: 45" (1143 mm)
• Weight: 75 pounds (34 kg)
• Hull Mid Depth: 1' 2" (356 mm)
• Draft: 4.5" (114 mm)
• Water Line Length: 13' 11" (4.2 m)
• Water Line Width: 37" (940 mm)
• WLL/WLW Ratio: 4.5:1
• Hull Speed: 5 knots, 9.3 kph, 5.8 mph

Mandarin 17'

• Length: 17' (5.2 m)
• Beam: 45" (1143 mm)
• Weight: 85 pounds (39 kg)
• Hull Mid Depth: 1' 2" (356 mm)
• Draft: 4.5" (114 mm)
• Water Line Length: 16' 0" (4.9 m)
• Water Line Width: 37" (940 mm)
• WLL/WLW Ratio: 5.2:1
• Hull Speed: 5.4 knots, 10.0 kph, 6.2 mph

Construction:

Both boats can be built three different ways (plans support all three):

1.    Stitch and glue with plywood planks

2.    Carvel planked on frames with plywood planks

3.    Strip planked with solid wood on frames modified to eliminate flat spots.

Overview of the plans for the Mandarin 15' (top) and 17' [Drawings source]:

15' Mandarine

 

17' Mandarine

Owner Views

Video of a Mandarin 17 rowing.

An interesting capability of the Mandarin 15 is that she can be built in two halves, split at the center seat.

Mandarin 15' Half

Bill Martin built his 17' version using strip planking...

Bill Martin's 17' Strip Built Mandarin...

...and Interior View

Paul Kirwin's Mandarin 17 Beautifully Fitted Out (including a needlepoint cushion)

A Mandarin 17 in Light Chop

Conversion to an Oar Cruiser:

• Add 2 bulkheads (with water-proof access hatches) separated by 7' (2134mm), centered in the hull to provide a cockpit and sleeping area.
• Provide decking to create a 5' (1524mm) long cockpit opening, approximately 2' (610mm) wide.
• Add a 4" (102 mm) coaming on all sides of the cockpit opening.
• Add cross-slatted floor boards that span the bottom 4 planks for the full length of the cockpit.
• Provide foot braces and a rowing seat that would lock into the floor boards.
• Add temporary shelter to provide protection in inclement weather.

Summary-Pros:

• Large enough to provide storage space for equipment and supplies.
• Narrow hulls with minimum wetted surface (due to 'round bottom' design) and high WLL:WLW ratio (4.5:1 and 5.2:1) result in higher cruising speed than many Oar Cruisers.
• Low windage.

Summary-Cons:

• Longer build time than other plywood panel-built boats.
• Depending upon which build method is used, weight of boat will vary.

Bolger's Cartopper

(Also see the write-up for Cartopper converted to an Oar Cruiser, published Jan. 8, 2017.)

I'm infatuated with small and simple: especially boats. Matt Layden's Sand Flea (go here for lots of photos of it) is a prime example...so is his Paradox, Enigma, etc. I especially like <12' (3.7m) because there is no registration required (in my state). Following is an example of small is beautiful...

Cartopper, one of Phil Bolger’s prettiest small boats… 11’6” by 4’ (3.5m by 1.2m), double chine with a bottom 2’ (61mm) wide… (one person) loaded water line width is about 3’ (91mm). She is built with taped seams from 4 sheets of plywood and weighs approximately 90 pounds (40.1 kg).

Johnny O'Neill's Cartopper

With either a boomless sprit sail (with peak vang) or a leg-o’-mutton (with sprit boom, as pictured above), both approximately 60 square feet (5.6 m), she sails well as long as weight is kept amidships. The boomless spritsail rig enables all spars to be carried inside the boat.

Phil Bolger’s comments from his Boats With an Open Mind (chapter 7) book:

“…the sheer and flare produce an exceptionally dry boat in choppy water; she can carry three sober adults over a fair-sized powerboat wake…” 

“…Cartoppers row well as long as they’re trimmed with one person… and as long as they’re not rowed hard. The short waterline makes waves rather than speed, with effort, even with a light load…” 

“…The open interior allows an adult to lie down at full length…”

The complete set of plans, including a table of offsets, are include in chapter 7 in BWOM… Included in those plans is a diagram of a full length tent that provides ventilated sleeping room for one and sitting headroom.

Overview of the Plans

Plans, along with builder notes (not included in the BWOM chapter) are available from H. H. Payson and Company.

Lane Kendall has documented with photos and narrative the building of a Cartopper... well worth the time to review for the building process for Cartopper as well as any taped seam construction.

Jim French built a Cartopper without the sailing rig (rudder, centerboard and mast) strictly for rowing.

Jim French's Cartopper for Rowing Only

He added a second rowing station to enable rowing with a passenger, and maintaining reasonable trim.

Jim French with Passenger

Grapeview Point Boatworks restored a Cartopper, adding floorboards and a stern seat.

Cartoppper Restored by Grapeview Point Boatworks

As designed, Cartopper, with the addition of a tent (as Bolger has specified) and an ‘air mattress’, would make a pretty oar/sail micro cruiser suitable for protected waters. If I were to build her as a ‘pure’ oar cruiser (as defined in this blog), I’d do the following:

• Eliminate the sailing components (maybe)
• Add floor boards covering 7’ (2.1m) of the bottom
• Add fore- and aft-decks to minimize the size of the cockpit (to about 4’ [1.2m]), with flotation built-in and room for personal gear (in waterproof bags)
• Provide for weather protection while eating and sleeping.

What a beautiful little oar cruiser she’d be!

Comments welcome...

Piloting Part 6, Rowing in the Wind

“While not pleasant, rain has little adverse effect on rowers. Heat stress can be a problem for athletes, but the major impact is wind speed and direction.”

BBC July 28, 2012 in discussion about rowing events at London Olympics 

“Sailing would be great if it wasn’t for the calms…
Rowing would be great if it wasn’t for the winds.”
                                                                          T. Clarke 2016

 

Impact of Wind on Rowing

Klaus Filter of the DDR (Deutsche Demokratische Republik), in 1970s, using a wind tunnel, measured the impact of wind (strength and direction) on rowing racing shells of 1-, 2-, 4- and 8-person crews. It is summarized below, extrapolated from his data posted in the Rowing Biomechanics Newsletter.
I combined the data for the four different racing shells since the differences among the 4 were all less than 5%, in most cases only 1% or 2%. Wind direction is relative to course… 0° is a head wind and 180° is wind directly from the stern. Wind speed is given in meters/second and miles per hour. The tabular data is the percent impact on speed.

Per Cent Impact on Speed as a Function of Wind Speed and Direction

The key ‘takeaway’ from this chart, for me, is not so much the percent cost, or benefit, from the wind, but rather it is how the course relative to the wind direction impacts speed… rowing against the wind costs a lot more than the benefit of rowing with a wind of the same speed.
And rowing at an angle to a headwind (tacking, in effect) eases the drag (slightly), but increases the distance to be rowed. See Small Boats Monthly article on Tacking for Rowing.
For the oar cruiser, the percent impact would be greater than in the table above, since the oar cruiser has much more aero drag than the racing shell. How do we calculate the aero drag of an oar cruiser?
The formula for determining aero drag is:

Aero drag (pounds) = .0034 x S x C x V x V where:

.0034 is a constant

 S is the square feet of frontal area exposed to the wind

C is the “drag coefficient”… for simplicity we’ll use “1”

V is the velocity of the wind over the boat.

What is the square feet of frontal area exposed to the wind for a typical oar cruiser?

It’s the frontal area of the boat itself (let’s assume 4’ wide and 18” high for 6 sq. ft.) plus the exposed portion of the rower (assume 2’ wide by 2.5’ above the gunnel for 5 sq. ft.) for a total frontal area of 11 sq. ft.
“V”, velocity of the wind is the wind speed in miles per hour plus the speed of the boat (if a headwind… minus boat speed if heading downwind). Let’s assume a 10 mph head wind and a boat speed of 3 mph for a V of 13.
Plugging these numbers into the formula, we get:

Boat aero drag = .0034 x 11 x 1 x 13 x 13 = 6.3 lbs of aero drag from a 10 mph head wind.

There is another aero drag component that Klaus Filter mentions in his article. And it is a component that we can control… to feather the oars or not.
Lets assume I’m using a set of oars 94.5 inches (a little less than 8 feet [2.4m]) long, with a gear ratio of 2.5 (end of blade to oar lock [67.5 inches] divided by oar lock to end of handle [27 inches]). Let’s further assume the blade is 5” by 24”, which is .83 sq. ft.

When I’m rowing, the handles will move through an arc let’s say 2 feet long. This means the blades will be moving through an arc 2.5 times as long… 5 feet. If I’m rowing at 3 mph at a stroke rate of 20/minute, the blades are moving 5’ under water (no windage), but during recovery they are moving 5 feet in 1.5 seconds (2.3 mph) added to the boat speed of 3 mph for a total of 5.3 mph. If the wind is blowing at 10 mph, then V (velocity of wind over the oars) is 15.3 mph. Plugging these numbers into the formula, we get…

Oars aero drag = .0034 x 1.66 x 1 x 15.32 = 1.32 pounds. 

But since the oars are moving against the wind only half the time, the actual aero drag from this set of oars under the given conditions is 0.66 pounds.
To put this into the context of the real world, we need to add yet another drag component… let’s call it ‘water drag’, which is made up of skin resistance, form resistance and wave resistance.  A complex calculation, but Jim Michalak comes to the rescue.
Jim used his Roar2, which is 14’LOA and 42” wide, as his ‘test boat’. He found that the water drag was (slightly less than) 5 pounds at 3 knots. This figure came from a Hullform derived analysis of Roar2 which he then confirmed by measuring the force on the oars in his own Roar2.
Putting all this information together, we can come up with the following summary:

• Rowing a 14’ nicely shaped row boat at 3 knots in calm conditions (no wind, no waves) requires 5 pounds of force by the rower (to overcome the 5 pounds of water drag).
    
• Rowing a 14’ nicely shaped row boat at 3 knots against a 10 mph headwind requires 5 + 6.3 (=11.3) foot pounds of force by the rower, if the oars are feathered during recovery.
    
• Rowing a 14’ nicely shaped row boat at 3 knots against a 10 mph headwind requires 5 + 6.3 + 0.66 (=12) pounds of force by the rower, if the oars are NOT feathered during recovery.
  

Rowing in the Wind

As we calculated above, rowing against a 10 knot wind takes more than twice the energy than rowing in a calm. But what if it’s blowing 20 knots?
With a 20 knot headwind, rowing at 3 mph requires 24.8 pounds of force on the (feathered) oars, five (5) times the energy required for rowing in a calm…not a pretty picture.
See the post on Rough Water Rowing for tips on how to row when the wind picks up and waves are high. The key points:

• Row with shorter strokes and a quick recovery to maintain boat momentum,
   
• Loosen the grip on the oars… there is a tendency to grip stronger when rowing in difficult conditions, which tightens all muscles unnecessarily,
   
• Feather the oars and make the recovery higher to avoid hitting waves.

Rowing in a beam wind (90° to the wind direction) presents its own set of problems. In my Lillistone Flint, a beam wind causes the boat to turn into the wind…this, in spite of more windage from the bow vs. stern.
Rob Fisher and his son rowed a Welsford Mollyhawk in the 2016 Texas 200. He relates that at one point, when rowing in a beam wind of 20+ knots, they rowed for miles using only the starboard oars in order to maintain course. He felt that a rudder would have helped.
My own thinking is that the ends of the boat should be low (with fore and aft decks added) in order to reduce windage in beam winds. For me, rowing into a headwind is just ‘grunt’ work. But rowing with a strong beam wind is more difficult because the impact on rowing varies and I’m always pulling harder with one oar or the other to keep on course.

The Fine Print...

I’m not a professional pilot. I try to be accurate and I check my information, but I’m not perfect. This post is for information purposes and is intended to be only a starting point for learning the skills of piloting. As with any activity with a small boat, there is always the opportunity for ugly surprises. Practice the skills under ideal circumstances and you’ll increase the probability of being able to use the skills during an ugly surprise to keep you and your boat safe.