Next Boat?

Should there always be a "next boat"?  Creating another boat design is always rewarding: changing a mental vision into something that is real; something you can see and touch.  The work of creating and building is a pleasurable challenge, but how many boats can one person use?  I only have space for one full-size boat.  To completely equip a new boat is far from cheap.  And there is no guarantee that the new boat will be better, only that it will be different.

With that in mind, I started on a new design.  The guiding idea was to create something with more curvature to be more visually interesting but maintain an uncomplicated build sequence.  A forward sloping bow profile with more lateral flare provides a more modern look and will also be easier to plank.  The raised foredeck of my previous build added complication to the build and would not blend well with the flared bow; thus, it was deleted.  The vertical stern on the previous build was helpful in providing internal volume for flotation foam, but it was esthetically bland.  The new hull would have a forward sloping stern.  The topsides avoid any slab-sided sense by continuously transitioning from significant flare forward to significant tumble-home aft.  In fact, tumble-home has been reduced to be more in harmony with the added beam forward.  Added beam means more usable cockpit space.

The result, if built full-size, would be a hull 18 1/2 feet long by 6 feet 3inches wide with a 12 1/2 degree deadrise for about the aft 1/2 length of the hull.  Of course, the hull surface is fully developable which simplifies construction and provides exact dimensions.

If you can't build the full-size boat, a model helps to visualize what has been designed and also really clarifies construction details.  Thus, I built a model at 1/6.25 scale (alternately expressed as 0.16 scale) which gives a model about three feet long.  I had enough scraps from previous projects to provide all the parts.  At this point I regret not spending more time creating a rigid strongback building form.  Some of the frames shifted as parts were bonded together resulting in a slight distortion in the model, but it still is accurate enough to serve its purpose.  And I was able to visualize

a much better strongback design to be used if the hull were ever built full size.  For now, the next boat is a dream.  Owner designed, home-built wooden boats are hard to sell.  I need more time to enjoy the boat I completed last spring, and a new boat would take about two years, spare time.  Anyone looking for a design to build?

                  

A Day at the Lake

Not much to report.  This summer in Colorado has been unusually cool and rainy, providing fewer dry, sunny days for boating.  Yesterday we did take the boat out and had a bit of an adventure.  Friends brought their boat, a 21' pontoon boat, also.  I had checked the weather forecast before leaving; nice weather until mid afternoon when wind and possible rain was predicted.

We joined up with our friends, who anchored their pontoon at the entrance to a small bay, for lunch on the pontoon's broad deck.  Everyone was enjoying the beautiful weather and showed no concern about a possible change later that afternoon.  Then my wife, myself, and our friend, Roger, left in our boat to explore the lake which was several miles long.  His wife and her two sisters stayed on the pontoon.  As we headed up the lake, the wind picked up, and whitecaps started to appear.  The waves continued to build, but by now we were at the upper end of the lake where we were somewhat protected.  As we came downwind along the opposite lake shore, I was able to make out the pontoon in the distance and noticed that it was no longer anchored in the center of the small bay, but drifting toward the shore.  When I pointed it out, Roger agreed we better get over there to see what had happened.  As we crossed the lake we met with the full force of the waves, 2-3 feet high.  We lowered our bimini to reduce windage and took some spray in the cockpit from occasional waves breaking on our starboard side.

When we got to the pontoon, it was being pounded on the rocks on the lee side of the bay.  The three women on the pontoon had decided that the anchor was dragging so they started trying to pull it in.  They did not take down their boat's bimini; they did not start the motor and use it to position themselves over the anchor.  Thus, their efforts to bring in the anchor only accelerated the effects of the strong wind and waves which quickly pushed their boat onto the rocky shore.  My job was to get our boat as close as possible so that a tow line could be passed.

The wind and waves were too strong to keep the bow of our boat into the wind while maneuvering slowly, and I wanted to keep our propeller as far as possible from the shallow rocky shore.  So I approached the pontoon bow first with the waves breaking against our stern.  The engine splash well and covered rear deck were valuable in keeping our boat interior dry.  Roger went over the side (with a life preserver), waded chest-deep to the pontoon, and passed a tow line to our runabout.  Then it was just a matter of putting our 75hp Evinrude in reverse and backing off, pulling the pontoon with us.  I wasn't sure that the prop would have enough reverse thrust for the task, but it worked well.

Once we were free of the shore, they were able to get their engine started and the tow line was returned.  We headed for a somewhat sheltered marina which was further downwind.  With the wind and waves behind us, we were able to surf the face of waves, and it became an enjoyable run.  On later inspection of the pontoon, the actual aluminum tubes had been protected by aluminum angles welded onto the tubes to act as strakes which minimized damage.

It frustrates me that all the women involved showed so little interest in learning competent boat handling.  This entire situation could have been avoided.  What happens if they encounter a more serious situation in the future?  People die from simple errors.       

Resting on its design waterline

If my wife were sitting in the forward seat, the boat waterline would be about exactly where I painted it.  Calculating displacement takes place very early in the design process.  This hull has a 12-degree deadrise. If I increased the deadrise, then something else would also have to change:  increase displacement (weight), shorten the waterline length, or risk the hull riding above the major chine which would decrease stability and may cause the hull to be louder at speed from water slapping against the hull bottom.

Increased deadrise will make the hull ride better in waves and may increase directional tracking, but it also could require more power to maintain planing speed.  Everything is a trade-off.

At Flaming Gorge, Utah

A planned trip to Pueblo Reservoir had to be cut short because of an electrical short in the power tilt/trim switch.  Diagnosis was difficult; installing a new switch was simple.  There was a crack in the rubber cover for this switch which, after a period of use, allowed moisture intrusion to complete the circuit.  This past week we went to Flaming Gorge Reservoir in Utah for some real boating.  The lake extends into Wyoming for 75-100 miles filling a deep and scenic gorge.  We explored the lake for 30-40 miles and encountered some wind and waves.  It is a light boat with little draft so, when maneuvering into the dock with a wind present, we lower the bimini top to cut windage.  Also, when cornering while planed out, the hull will skid; when cornering while accelerating onto a plane, the hull will bank well and turn sharply.  There is almost no bow rise when accelerating, and the hull rides smoothly and cuts through moderate waves with no fuss.  I switched to a 15" pitch prop for this trip.  We were operating at 6000' altitude, and the engine achieved 4700 rpm, easily exceeding the 35 mph maximum speed of the speedometer dial.  The "sweet spot" for this engine is supposed to be 5000-5200 rpm and our next outing is at Grand lake, over 9000' elevation, so I have ordered a new 13" pitch stainless steel propeller which, hopefully, will be perfect for these circumstances.  I have to think that, if we were near sea level, this boat would easily exceed 40 mph or, alternately, I could have installed a somewhat less powerful engine.

I haven't yet mentioned that this new boat fits our trailer perfectly, much better than the previous boat.  We trailed it 400+ miles to the lake; other than a decrease in acceleration, you couldn't notice that we were towing.  Although I can't find anything design-wise to improve on this boat, I am always evaluating what could be made better/ more esthetically pleasing on a next boat.  This is a 12 degree deadrise hull; I wonder what a 14 degree deadrise would do to performance?  I have an idea for a more modern-looking runabout which I hope to publish here in the near future.  I already have all the offsets and need to make up some drawings.  Then perhaps construct a model.

    

What a day!

Having been busy/out-of-town the past few weeks (a trip to the Galapagos islands), this week was finally the chance to take the new boat out.  I picked a nearby (50 miles away) small reservoir knowing that this was a test run with possible complications.  The boat performed well; however, there are still adjustments to be made.  In a few spots at the transom, the red bottom paint came off.  I don't expect it to be difficult to repair; probably just a light sanding and thorough cleaning to improve adhesion.  The engine RPM topped out at 4200 which is below the recommended range of 4500-5500.  I was using a 17" pitch propeller and will need to switch to a 15" or 13", both of which I have on hand.  The indicated speed was 35+ mph due to the speedometer only reading to 35 mph.  I need to decide if I should replace the speedometer.  We had three people and 8 gallons of gas on board with the bimini top up.  The boat accelerates quickly with very moderate bow rise and vision is good from the driver's seat.

I want to view and photograph the boat at speed, but we will need a second boat for that.  On this lake the shore areas are "No Wake Zones".  The reason for the "What a day!" label for this entry is because when we arrived home from the lake, and I was putting away the boat, I developed some stomach discomfort which quickly worsened into acute appendicitis.  We went to the emergency room, and within a few hours my appendix was removed.  Now no strenuous exercise for the next six weeks.

The new boat looks complete.

Finally, the windshield is completed.  My wife encouraged me to have a metal windshield frame, but now that it is done, she says that the wood looks better than a metal frame.  But she thinks that it should have been taller.  I considered the height, angle, and fore-aft placement of the windshield when designing it; both from an esthetic and functional aspect.  Unless you make the windshield quite tall, the upper edge of the frame is in your field of vision.  Tall would have not fit the esthetic I desired; most of the time I expect to be viewing ahead over the top edge of the windshield.  I had an extra cushion made for the captain's seat to raise the line-of-sight.

And the upholstery is completed.  The seats are separately removable, allowing access to the fuel tank under the front seats and access to the battery and storage behind the rear seats.  A person could do their own upholstery, but it is not an area I have any expertise in; so I contracted it out.  And the bimini top with full enclosure panels is complete as well as a travel cover.  Looking over the amount of detail in all those panels, the variety of materials required, and the expertise involved, I am glad to have it done professionally.  Bringing the boat home, I had to drive through a spring snow storm; the boat and cover were wet and dirty when I arrived at our garage.

The boat is still not done, but we are in the home stretch.  I need to bundle and strap the control leads, electrical wiring, and fuel lines in place.  There is one slight scratch in the paint to touch up.  I need to get the boat inspected by the State of Colorado to get a Hull Identification Number (HIN) for licensing.  Then we will be on the water.  Here in Colorado, the scenic mountain lakes aren't warm enough for boating until June.  We may end up towing the boat to lower altitudes for a longer boating season.

       

Why I use rosin paper

I recently read an article concerning conversion of developable surfaces into flat sheet patterns.  In previous posts, I really haven't discussed how to do that using a mathematical approach.  It can be done; I used this approach when I built a 20 1/2 foot sharpie design many years ago.  The only reason I haven't expanded on the subject is that, once I have a hull framework constructed, it is easier to simply make a stiff rosin paper pattern by laying a roll of paper over the framework and tracing the edges.  But, for those who do not want to construct a full hull framework, being able to go directly to laying out patterns for sheathing may be worthwhile.

The method utilizes what may be best called external triangulation.  It is external because we are not calculating distances just between points within the design surface but instead are using our conic apex, located at some distance from the surface borders, as a reference point for many measurements.  Using the coordinates of the apex in conic development and the coordinates of consecutive points along the chine of the hull, we can calculate the length of radiating (ruling) lines emanating from that apex.  The chine of the hull is created using a mathematical equation; thus, by integrating this equation (the power of calculus) we can find an equation [it is a long but standard equation] to calculate the distance along the curve between any two designated points on the chine.  Those points along the chine provide the third distance in creating a series of triangles which, when plotted in sequence, will give us the shape of the developed surface.  However, part of the chine curvature may be contained within the outline of the surface itself; thus the sequential points of the chine are best first plotted along a fair batten which is then laid in place and connected to the ruling lines from the apex.  For parallel projections, instead of an apex, we would be plotting parallel ruling lines.  If you calculate the distance between two sets of coordinates in a developed surface NOT connected by a ruling (straight) line by using simply the formula square root of (x squared plus y squared plus z squared), the distance will be distorted by lack of consideration for the curvature present.

In conclusion, yes, I can create flat surface patterns for sheathing.  But is it really worth the effort when a roll of rosin paper will give me the same thing?   

Pictures of boat windshield

The windshield was constructed in four separate sections.  Each section shape was calculated using the x-y-z coordinates available because the entire hull shape was created numerically before any construction began.  Junction angles between sections, and between the windshield and deck could also be pre-calculated.  Because some error can be anticipated in any human-constructed shape, the four sections of the windshield were then bonded together while positioned on the actual hull deck.

When finished, the windshield will be bonded to the deck and fastened with screws from underneath the hull decking.

I'm getting excited about what it will look like after the interior is upholstered (not by me).  The same people will also make a bimini top, full foul weather enclosure, and travel cover.  By the time I get it back, the weather will be warm enough to finish the windshield details for final installation.

Winter progress

Sorry for the lack of recent posts; the winter weather and some logistical problems have slowed things down.  My previous boat has been transferred to a new owner and is now residing in Montana.  The new boat has been transferred to the trailer and fits it perfectly.  The new 75hp Evinrude E-Tec engine has been installed, and all the controls have been connected.  I still need to organize tubes & wires by wrapping and strapping them under the deck.  I had wanted a stainless-steel windshield frame, but no matter how exact and simple I made the proposed design, the metal fabrication shop still estimated the cost at $4000-5000 which just didn't fit my goal of producing a good boat at a moderate price.

I bought a plank of African mahogany for $68 and built my own windshield frame.  I have had the glass cut and fit for the frame.  The glass people said that they think the wood frame will look nicer than metal.  Nice to hear such comments.  The wood frame has been fabricated in four sections.  Although the four sections fit together well, I want to bond them together with epoxy while they are in place on the hull foredeck for a strong, accurate result.  The boat is now in our unheated garage with outside temperatures mainly below freezing.  The epoxy will require warmer temperatures.  It may be a while before the final assembly of the windshield takes place, but, in the meantime, I can clamp and screw the windshield in place well enough to have a boat cover fabricated.

The windshield frame was designed mathematically.  It is a system which works incredibly well for me.  Everything is done in an X,Y, Z coordinate system.  After building two mock-ups, I elected to build a windshield 12.5 inches high which slants aft 10.5 inches from bottom to top and is 53.5 inches wide with rectangular sections.  Knowing also the offsets of the deck curvature, I was able to calculate the angle of intersection of the two front panels, 16.54 degrees, the angle of intersection of the front panels to the deck, 42.48 degrees, and the angle of intersection of the side panels to the deck, 9.09 degrees.  All the linear dimensions were calculated to similar accuracy.  When cut to those angles in the shop before assembly, the panels fit together well.  I can't imagine how much more difficult it must be to use trial-and-error, cut-to-fit methods.

We were in Bocas Del Toro, Panama recently and I brought back some pictures of abandoned, hollowed-out-log cayucos and the pangas which have replaced them to a great degree.  When we lived there 30+ years ago, our local maid said she wouldn't trust a boat which was made with adhesives instead of from a single tree trunk.  Times have changed.