Experience Using Outboards on PDR
By Jonathan Huddleston #1068 "INSIDIOUS BUFFLEHE" (5ar)Good Evening Shorty,
I've got a quick report regarding the use of outboards on a PDR. So, after having sailed the Insidious Bufflehead several times now, I've been contemplating a South to North navigation of the entirety of Lake Eufala in Oklahoma sometime next year. This will likely be a serious stretch as it's approximately 47 miles and a single day in PDR will be a long one.
While thinking through the logistics of this, one of the concerns was what if I don't make it in a day, and my camper is on the other end of the lake etc. etc. One idea that I had was that if I just mounted an outboard to my PDR that was capable of say, 15 to 20mph ish, I could quickly escort myself to the camper if I came up short, sleep in my camper, then the next morning escort myself back to where I left off the day before, and finish my sail...
So being the addicted motorhead that I am, I just happened to have a 15 horse 1970's something Montgomery Wards outboard lying around that I had acquired a few years back for a fifty dollar bill. I didn't even know what I would put it on at the time, but it promised to turn money into sound, and it was really cheap, so of course I brought it home. After doing a few basic preventative maintenance items it was clamped to the transom, which was originally built with this possibility in mind. First time at the lake was... interesting. It works great to about 6-7 mph, but the nose is really high. After that, the deck angle begins to get, well... interesting. Somewhere in the 8.5 to 9 range, the wake is taller than the boat, and the lake starts to come along for the ride without asking permission to board.
This being clearly unacceptable, and being an aeronautical engineer by trade. I spent my coffee break the next morning explaining to my co-workers the unexpected result of this wildly pitched up motoring issue. They too engineers, and self proclaimed tinkerers I might add, began to consider alternatives. Before it was all over the following things happened: Lots of math. Lots of science. Lots of projections based on opinion. Lots of opinions based on assumptions. More opinions based on opinions by people of questionable understanding. Dynamic pressure equations and even spreadsheets based on these hypothesis. Finally it became apparent that something REAL had to be done. Over the course of the next several nights, and even during a few spelling word practice sessions with my kids, I built a hull extension which continued back to the transom as a straight line from the 'flat spot'. Basically it was a 4 foot wide six inch tall triangular shaped plug which would trick the lake into thinking that I had built a different boat.
After referring to the project as the 'the boat plug' for a few weeks, one of my engineer friends at work told me one day that if this thing was ever going to be marketed with any hope for profit (totally kidding by the way) I had to quit calling it the 'boat plug'. I hear him mutter something about it kind of sounding like you'd just hit something and were looking for a tree branch the right diameter to knock into the hole so that your $300 boat doesn't go straight to the bottom before you make it back to the dock. I laughingly suggested that it needed an X or a Z in it to be truly spectacular, and shortly thereafter the VEDA xi was born. (Velocity Enhancing Displacement Apparatus, 6inches) He kinda looked at me weird for a minute before I explained that while the math and science part had to work, the Roman Numerals didn't actually have to make sense, because after all, this part was just to sound good for the commercials and I could go right ahead and use my 'X'. You know, to make it cool.
Caulking, painting, more painting, flip it over paint the sides that were holding it up, let it dry. Ready? Yes! Nope. We should make a tapered wedge to smooth the water flow over that 1/4 inch transition! Cut some white fir. Un-jam table saw bevel adjuster. Make another cut on the fir. Paint. Flip. Paint. Look at project truck. Paint spot on truck hood while brush is still wet to sample color. Let it all dry. Ready? Yeah! Nope. 34 degrees and rain for two weeks straight. Lakes are all full now, Saturday is supposed to be good. Saturday it is misting and 10 degrees cooler than forecast, but the packing tape joints that hold this thing on are already getting wet from the rain, so why not? We take it to the lake.
Pitching problem solved. Nice smooth acceleration, little bit of nose up, but so much more controllable. Until the prop cavitates at about 5.5 mph. This is as fast as she's going to go. I'm not going to try cutting a notch in my transom to lower the motor, after all I was planning on leaving the plug in the dumpster and going home with my original class legal boat. So there's nothing left to do but some additional tests. We GPS check maybe a .3 mph drop in speed with a constant thrust electric motor that we've tested before without the VEDAxi taped in position. We're a bit heavier today with two adults instead of an adult and one kid, so the additional drag pulling a square corner through the lake at sailing speeds is very low, if it's even real. Let's find out how it sails with the new mod. Speed wise, its about the same, handling wise, there are a few differences. MUCH more difficult to tack all the way through the wind with the bottom square all the way to the back. We assume it's working something like a shoal keel would. Most noticeably though, the nose sits lower due to the increased buoyancy in the rear. This makes it want to pound into waves rather than ride up over them, and also makes it much more difficult to sail flat, even with two adults to shuffle weight around. Overall I guess we'll give up on the idea of having the best of both worlds in a $300 package. But hey, we did get a cool 'X' to throw in there, even if the kids have learned that it doesn't spell 6!
Hope this information is helpful to the myriad of PD builders who might be curious about the same characteristics of your neat little boat like I am. I've included some pictures of the plug, excuse me, the VEDAxi. Thanks again for the cool little design and the many hours of enjoyment building, sailing, and now experimenting that your boat has provided.
Jonathan Huddleston
NE Texas
I've got a quick report regarding the use of outboards on a PDR. So, after having sailed the Insidious Bufflehead several times now, I've been contemplating a South to North navigation of the entirety of Lake Eufala in Oklahoma sometime next year. This will likely be a serious stretch as it's approximately 47 miles and a single day in PDR will be a long one.
While thinking through the logistics of this, one of the concerns was what if I don't make it in a day, and my camper is on the other end of the lake etc. etc. One idea that I had was that if I just mounted an outboard to my PDR that was capable of say, 15 to 20mph ish, I could quickly escort myself to the camper if I came up short, sleep in my camper, then the next morning escort myself back to where I left off the day before, and finish my sail...
So being the addicted motorhead that I am, I just happened to have a 15 horse 1970's something Montgomery Wards outboard lying around that I had acquired a few years back for a fifty dollar bill. I didn't even know what I would put it on at the time, but it promised to turn money into sound, and it was really cheap, so of course I brought it home. After doing a few basic preventative maintenance items it was clamped to the transom, which was originally built with this possibility in mind. First time at the lake was... interesting. It works great to about 6-7 mph, but the nose is really high. After that, the deck angle begins to get, well... interesting. Somewhere in the 8.5 to 9 range, the wake is taller than the boat, and the lake starts to come along for the ride without asking permission to board.
This being clearly unacceptable, and being an aeronautical engineer by trade. I spent my coffee break the next morning explaining to my co-workers the unexpected result of this wildly pitched up motoring issue. They too engineers, and self proclaimed tinkerers I might add, began to consider alternatives. Before it was all over the following things happened: Lots of math. Lots of science. Lots of projections based on opinion. Lots of opinions based on assumptions. More opinions based on opinions by people of questionable understanding. Dynamic pressure equations and even spreadsheets based on these hypothesis. Finally it became apparent that something REAL had to be done. Over the course of the next several nights, and even during a few spelling word practice sessions with my kids, I built a hull extension which continued back to the transom as a straight line from the 'flat spot'. Basically it was a 4 foot wide six inch tall triangular shaped plug which would trick the lake into thinking that I had built a different boat.
After referring to the project as the 'the boat plug' for a few weeks, one of my engineer friends at work told me one day that if this thing was ever going to be marketed with any hope for profit (totally kidding by the way) I had to quit calling it the 'boat plug'. I hear him mutter something about it kind of sounding like you'd just hit something and were looking for a tree branch the right diameter to knock into the hole so that your $300 boat doesn't go straight to the bottom before you make it back to the dock. I laughingly suggested that it needed an X or a Z in it to be truly spectacular, and shortly thereafter the VEDA xi was born. (Velocity Enhancing Displacement Apparatus, 6inches) He kinda looked at me weird for a minute before I explained that while the math and science part had to work, the Roman Numerals didn't actually have to make sense, because after all, this part was just to sound good for the commercials and I could go right ahead and use my 'X'. You know, to make it cool.
Caulking, painting, more painting, flip it over paint the sides that were holding it up, let it dry. Ready? Yes! Nope. We should make a tapered wedge to smooth the water flow over that 1/4 inch transition! Cut some white fir. Un-jam table saw bevel adjuster. Make another cut on the fir. Paint. Flip. Paint. Look at project truck. Paint spot on truck hood while brush is still wet to sample color. Let it all dry. Ready? Yeah! Nope. 34 degrees and rain for two weeks straight. Lakes are all full now, Saturday is supposed to be good. Saturday it is misting and 10 degrees cooler than forecast, but the packing tape joints that hold this thing on are already getting wet from the rain, so why not? We take it to the lake.
Pitching problem solved. Nice smooth acceleration, little bit of nose up, but so much more controllable. Until the prop cavitates at about 5.5 mph. This is as fast as she's going to go. I'm not going to try cutting a notch in my transom to lower the motor, after all I was planning on leaving the plug in the dumpster and going home with my original class legal boat. So there's nothing left to do but some additional tests. We GPS check maybe a .3 mph drop in speed with a constant thrust electric motor that we've tested before without the VEDAxi taped in position. We're a bit heavier today with two adults instead of an adult and one kid, so the additional drag pulling a square corner through the lake at sailing speeds is very low, if it's even real. Let's find out how it sails with the new mod. Speed wise, its about the same, handling wise, there are a few differences. MUCH more difficult to tack all the way through the wind with the bottom square all the way to the back. We assume it's working something like a shoal keel would. Most noticeably though, the nose sits lower due to the increased buoyancy in the rear. This makes it want to pound into waves rather than ride up over them, and also makes it much more difficult to sail flat, even with two adults to shuffle weight around. Overall I guess we'll give up on the idea of having the best of both worlds in a $300 package. But hey, we did get a cool 'X' to throw in there, even if the kids have learned that it doesn't spell 6!
Hope this information is helpful to the myriad of PD builders who might be curious about the same characteristics of your neat little boat like I am. I've included some pictures of the plug, excuse me, the VEDAxi. Thanks again for the cool little design and the many hours of enjoyment building, sailing, and now experimenting that your boat has provided.
Jonathan Huddleston
NE Texas
