Off Center Harbor blogs seem like they might be a good place to try to discuss some technical issues in boat design. There are lots of books on these subjects, many of them written by people with greater credentials and writing skill than I possess. But still, the blog-and-comment format available here would seem to offer some advantages. I can ramble o about some issues that seem to constantly come up in conversations with customers who are interested in design, and respond to readers’ questions about stuff that they could never quite otherwise get—and they might even get an answer that makes sense. But I make no promises.
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robert jones says:
Finally at 63, my first thought is, “how small of a motor can I use, and how small of a boat can I get away with”?
It took a while but now I’m “cruising” on my 45 year old, 19′ O’Day Mariner.
robj
Denis Noble says:
For my 20′-0″ outboard-powered launch, now stretched to around 23′-0″ with motor-in-a-well, the designer David Payne recommended 15 to 20 hp. The Yamaha retailer here asked first “What speed”, then said “You don’t need 20hp or even 15hp, For your 6 to 7 knots hull speed you’d do very well with a Yamaha High-Thrust 9.9hp.” When I checked with David Payne he agreed. I look forward to finding out!
Christopher Chadbourne says:
I’ll give two more reasons. At 8 knots you can read underway while on autopilot. At 8 knots you get time to “inspect” those other classic boats that you’re now passing more slowly.
Wesley Blazer says:
Doug, I work in the marine industry and it is always about more, more horsepower, more lights, more cupholders. In fact when co-workers look at my Lyman Islander, and see none of that stuff they disregard the boat all together. Until, they find out that with a 60 hp engine I can do the same 18 MPH they do with a 150 hp engine!
julio dongo says:
Thanks. Great explanation, take time to get salty and understand the logic that you explain clearly, after 10 years having planing yachts (cruise over 20 knts 44′ to 55′), I moved to semi-displacement (44′ to 65′) and with this experience I choose a 50′ slow semi-displacement I enjoyed cruise at 10 knts, fast cruise rarely used 16 knts.
Looking fwd for more
Julio
Bob Bilodeau says:
Doug,
You have my attention. Two years ago I decided to buy a 34 yr old trawler with just enough power to get around Chesapeake Bay at 7 knots or so. What impressed me the most about trawler designs was they offered lots of cabin space & comfort, were ultra stable in most sea conditions and operated pretty efficiently on a single diesel engine. While two diesel engines offered redundancy, I didn’t want to have to maintain two and decided one was adequate. As a result I have met more and more trawler owners and find they use their boats whereas the folks with the gas powered boats park them in the slips most of the time.
Lyons Witten says:
My Town Class sloop (17′) has oarlocks, should Mother Earth be feeling sleepy…
Alfred Fletcher says:
We don’t even have a motor. Ole Roz sails pretty good without.
Harry Bryan says:
Thanks Doug. Looking forward to more.
Dean Lohse says:
Love my Lawton Tender. Oars move it nicely in Florida inland waterways at 2-4 knots, and if I’m feeling lazy, my 2 hp Honda will get it all the way up to 4-6 knots. ‘Bout as fast as a need to go to enjoy the ride.
terry brower says:
Wooden sailboats: Best of both worlds. Built from renewable resource- driven by free, unlimited power.
terry brower says:
I sail on Elephant Butte Reservoir, New Mexico. When full it is about 40 miles long. Plenty big for my small sailboat giving me opportunity for some long days on the water if I choose. I watch the 70 mph plus bass boat roaring around easily getting to one end of the lake or the other in a few minutes. To me that would make me feel like I was on a farm pond. Of course they might not enjoy ghosting along at a few knots.
terry brower says:
When I bought a new 4 hp outboard for my 22′ Oday I was wondering if it was enough. Although it was on a calm day, and no current, my question was somewhat answered when I towed a 30′ Catalina back to port. Also when motoring alone I reach hull speed at slightly less than full throttle.
David Tew says:
I love going slow. We have a cabin motor launch with a 32 hp diesel that gets around comfortably at seven knots. That’s just fast enough to keep me attentive to avoiding the ever present lobster buoys where we live, but slow enough that I can enter into the conversations aboard. From July 4 through Labor Day we were under way for fifty hours and used forty gallons of fuel. Thus we got a ‘good deal’ this summer on a DP/H basis (Dollar and Pleasure per Hour) and can’t wait for next season.
James Robinson says:
At 89 years old, I’m slowly realizing these truths. Thanks.
Glenn Holland says:
Doug,
Thanks for the logic. When I’m at a show displaying my creek boats a question that is always asked several times is… “Now, how big a motor can I put on her?” I cringe and try to explain.
appreciate it,
Glenn