Experience With Outboards Part Next
By Jonathan Huddleston #1068 "INSIDIOUS BUFFLEHE" (5ar)'Morning Shorty,
In my last article (oh man, that sounds waaaay to official for anything that I might write) I mentioned that I had begun experimenting with the hull shape of my PDR, the Insidious Bufflehead as it is related to the best use of my 15hp outboard. (To clarify just a bit here: this is best as in most fun, most off the wall, and most likely to make a good campfire story following a recovery in ICU.) To quickly revisit those ideas I summarize in 7 quick points as follows: 1) Class legal PDR hull works great with an outboard up to about 4.5-5mph 2) Class legal PDR hull takes on water over the transom at approx. 9mph due to crazy nose high pitch attitude 3) I want to go faster than 9mph 4) I built the VEDA xi attachment to straighten out the bottom of the boat 5) My attachment fixes problem 2 above, but the prop cavitates and max speed is about 6-7mph 6) I’m not cutting my transom so we’re done here 7) no matter how it’s capitalized or punctuated, XI does not spell 6 in Roman Numerals.
If my original attempt had performed flawlessly, there is a small chance that I would have kept the quickly built version until it eventually disintegrated into waterlogged matchsticks. There is however, a very high probability that I would have thrown it in the dumpster and gone home thinking about a quick attachment method for a much more permanent version. As previously documented, my experiment did not succeed. This solidified in my mind the absolute need to keep the VEDA xi. When I got home, I drank some coffee while standing in the garage. I shifted my weight to my other foot and continued swilling coffee, while looking at the now soggy contraption taped to the bottom of my boat. MY CLAMPS ARE WET! I remove my bar clamps which were assisting the tape, kill a couple trees worth of paper towels, and realize that if I had just used my oil soaked garage rags instead of clean new paper towels, my clamps would have been dried AND oiled, the planet would have lasted a bit longer, and it would take slightly longer for PDR building material (also trees) to inflate to the point where I’m priced out of the hobby. Mentally noted for future self improvement…
More coffee.
What if I cut down that transom protector thingy that I built to keep my transom varnish from getting chipped/abraded/smashed by the outboard clamps? Out come the calipers. Chopping that thing up so that the motor can sit all the way down on the transom will save me 7/8 inch. What if I re-cut the curve in all the supports of the VEDAxi that fit the outer mold line of the bottom of the boat to lose a little more transom height? I use a combination of the calipers, an old metal ruler, a roofing square, a yardstick (free at your local paint emporium), some bricks, an old 2x4 block and a piece of shoestring and come up with some extremely precise fraction which was reeeaally important(?) to be incredibly accurate about. I’m sure it had like 7 significant digits, which is totally cool, because 1) according to Mrs. Bridgens in my 8th grade science class, fractions don’t have significant digits anyhow and because second) I have no earthly idea what the tolerance of my bricks was. Suffice it to say: a very unpretentious modification to the transom height of my VEDA xi equipped PDR was about to take place. Just with a lot of dubiously specific numbers attached to it. And without actually chopping into my boats no-kidding transom.
A template was made from the existing curved pieces of the VEDAxi. The template was pivoted around the forward end, while adjusting the height at the back. The template was taped in place. Stuff was stared at. Coffee was made. Stuff was stared at again while drinking coffee, this time so long that the tape came loose and allowed the peeeerrrfectly positioned template to come loose. The dog laughed at me. The template was repositioned. The curve was marked. The cuts were made. Stuff was test fit. Coffee was drunk while stuff was stared at. Stuff was waterproofed. More stuff was measured with bricks and shoestrings. Thought to myself “I can get just a little more”. Stuff that had already been waterproofed got cut again. The dog and the cat became friends and laughed at me together. Stuff got waterproofed again. I stared at stuff while stuff dried. I finally tape and clamp the thing back on the PDR. NOW I have a PDR attachment which makes an almost straight run back from the “flat spot” (almost straight because it’s a few degrees tilted up as it goes back, just in a straight line) AND most importantly the transom height is now 14 81/128” (I think I’m remembering that correctly it was soooo important that I can’t admit that I’ve forgotten the actual number).
Time to try this thing out. We (test crew today: me and my two kids) head out to our favorite spot which has a nice dock and the curve of the shoreline is just right with the prevailing wind to really keep the waves down most of the time. We launch the boat. We answer questions about the boat. (Side note to ANYONE who is considering building a PDR: You WILL spend time at the boat ramp answering questions about the boat every time you go to the lake. Every. Single. Time. I’ve loaned the PDR to friends so that they could take their wife/significant other out for a sail. They too, answered questions about the boat at the boat ramp. This is a good thing, unless of course you harbor a strong distaste for hobbies involving camaraderie. But it is in fact a thing. A very time-consuming thing. At the time of writing, I have not yet gone to a boat ramp that had no other people around and had to answer questions, but I fully expect it to happen eventually. Side note complete.) My son and I get in the boat, my daughter is on a tube 52’ 3” behind the boat (ski rope plus carabiner plus 1/2 diameter of the tube). Gimme a break about the tube, we fixed this! It’s going to work flawlessly right? We might as well go big or go back home. Why on earth wouldn’t you just go for broke and make the assumption that you can now pull a kid on a tube behind a $300 8 foot boat with a hull shape changing attachment half-taped, half clamped to the bottom?
Things work pretty well, but slow. Very. Slow. So slow in fact, that the excitement factor of this tubing experience soon has my daughter asking to be dragged (drug, drugged? I’m not nearly as good with grammar as I am with significant digits) through a field of lily pads so that she can collect some to give to Mom when we get home. First and only time that the excitement level of tubing has degenerated to this level of non-awesomeness. My now-driving-the-boat son concedes. At this point, it’s pretty clear that the prop cavitation thing is gone. Just as we intended, this is a by-product of the increased depth of the prop in the water. However, we don’t have nearly enough power to urge the two-up boat plus my daughter, plus the tube, and most recently, plus the lily pads, over the “hump” in the drag curve and plane out. The tube is very near planning, pushing a really big wave which usually happens just before it lets go and planes when we pull it with our big boat. It’s hard to tell for the PDR how near to the edge we are. We mess around a bit, detach the tube, and my daughter joins us in the boat. It’s very controllable, the pitching moment of the original hull shape is gone, the prop cavitation is gone, but we’re still pushing a really big wave at approximately 10mph, and don’t quite have the power to get on plane with three of us on board. This constitutes mild success as we’re going 10mph now (only 1 mph better than the previous 9, but it IS faster), and the lake is now oh so conveniently keeping it’s distance from the transom top.
The kids decide that they want to go swim and jump off the dock. So I let them out, and keeping very near the dock, I flog all 15 of those 1970’s Mail-Order Montgomery Wards horses into action. Action like John Wayne just jumped out o’ a taverns 2nd story window onto Dollor’s back kinda action. (Okay, okay, that was a slight stretch.) Maybe more like your neighbor’s old mare just regained consciousness after a surgical trip to the vet and is still borderline groggy from the anesthesia kind of action. Anyhow, by this time, the wind has shifted and our normally quiet cove is getting beat up with decent waves. (Fine, Fine, I’ll be truthful. They’re really more like growing ripples. At this point please don your 8 foot 15hp colored set of glasses, which will allow you to see ripples as HUGE WAVES for the remainder of the story. Also, we previously failed to do our lawyerly duty and will now remind you to keep your arms, hands, feet, hats, prosthetics and lunch inside the boat for the remainder of the ride.) HUGE WAVES that are making it kinda sketchy for a 16” high boat that’s only 8 feet long with a ludicrous amount of power. BUT IT WORKS! We slog for a second as we start shoving the bow wave and then just like that it lets go and planes! With the weight of just one person and an all up weight of 393lbs (96 hull, 62 outboard, 10 VEDAxi, 36 gas, 14 tools, 175 first mate (there was no captain, if there had been, he surely would have been smart enough to talk us out of this nonsense)). This thing will actually plane out! According to the age old rule of thumb, every 50 pounds of stuff should require about a hp. Based on the success with one person and unsuccess with the two kids on board, I think we’re probably a lot closer to 30 lbs per hp for a planing limit here. But we’re dealing with a very small flat plate area, and it’s a very short flat plate area to boot. Due to the HUGE WAVES (15 horse, 8’ boat colored glasses remember?) the very close proximity to the dock, and keeping an eye on my kids I failed to get a good GPS reading but I’m guessing it was probably somewhere in the 15-17 mph range. There are about 29 1/2 things I wish were a little more controlled for this particular test, but did I mention that IT WORKS! The prototype VEDA xi has now been confirmed as a success. It has achieved its hard-earned rest in the dumpster, and I’m left to return home, stare, drink coffee, and ruminate on a more easily detachable, more permanent version.
In conclusion Shorty, if you have other decent folks fettered with controversial judgment like me wondering if you can plane a PDR with a too-big-outboard, please let my ludicrous experiment be documented somewhere for the entertainment value of the masses. It’s not practical at all, but if you really, really, really want to, an 8’ PDR can indeed be built with a removable attachment that adjusts the hull shape to allow planing powerboat action with a 15hp outboard. With this small of a flat plate area and with this short of a boat, my suspicion is that it takes a lot more horsepower to get it to plane than it would take to keep it on plane once you crest your bow wave. You’re going to have to pay close attention to fore/aft trim. You’re not going to carry your whole family at speed. Your boat will likely beat you half to death in any kind of chop (or maybe she’ll just save herself the trouble and throw you out). Your cat and dog may experience newfound companionship at your expense. But… IT CAN INDEED BE DONE. I now know from personal experience that The Insidious Bufflehead, the smallest of all the diving ducks, can also fly.
In my last article (oh man, that sounds waaaay to official for anything that I might write) I mentioned that I had begun experimenting with the hull shape of my PDR, the Insidious Bufflehead as it is related to the best use of my 15hp outboard. (To clarify just a bit here: this is best as in most fun, most off the wall, and most likely to make a good campfire story following a recovery in ICU.) To quickly revisit those ideas I summarize in 7 quick points as follows: 1) Class legal PDR hull works great with an outboard up to about 4.5-5mph 2) Class legal PDR hull takes on water over the transom at approx. 9mph due to crazy nose high pitch attitude 3) I want to go faster than 9mph 4) I built the VEDA xi attachment to straighten out the bottom of the boat 5) My attachment fixes problem 2 above, but the prop cavitates and max speed is about 6-7mph 6) I’m not cutting my transom so we’re done here 7) no matter how it’s capitalized or punctuated, XI does not spell 6 in Roman Numerals.
If my original attempt had performed flawlessly, there is a small chance that I would have kept the quickly built version until it eventually disintegrated into waterlogged matchsticks. There is however, a very high probability that I would have thrown it in the dumpster and gone home thinking about a quick attachment method for a much more permanent version. As previously documented, my experiment did not succeed. This solidified in my mind the absolute need to keep the VEDA xi. When I got home, I drank some coffee while standing in the garage. I shifted my weight to my other foot and continued swilling coffee, while looking at the now soggy contraption taped to the bottom of my boat. MY CLAMPS ARE WET! I remove my bar clamps which were assisting the tape, kill a couple trees worth of paper towels, and realize that if I had just used my oil soaked garage rags instead of clean new paper towels, my clamps would have been dried AND oiled, the planet would have lasted a bit longer, and it would take slightly longer for PDR building material (also trees) to inflate to the point where I’m priced out of the hobby. Mentally noted for future self improvement…
More coffee.
What if I cut down that transom protector thingy that I built to keep my transom varnish from getting chipped/abraded/smashed by the outboard clamps? Out come the calipers. Chopping that thing up so that the motor can sit all the way down on the transom will save me 7/8 inch. What if I re-cut the curve in all the supports of the VEDAxi that fit the outer mold line of the bottom of the boat to lose a little more transom height? I use a combination of the calipers, an old metal ruler, a roofing square, a yardstick (free at your local paint emporium), some bricks, an old 2x4 block and a piece of shoestring and come up with some extremely precise fraction which was reeeaally important(?) to be incredibly accurate about. I’m sure it had like 7 significant digits, which is totally cool, because 1) according to Mrs. Bridgens in my 8th grade science class, fractions don’t have significant digits anyhow and because second) I have no earthly idea what the tolerance of my bricks was. Suffice it to say: a very unpretentious modification to the transom height of my VEDA xi equipped PDR was about to take place. Just with a lot of dubiously specific numbers attached to it. And without actually chopping into my boats no-kidding transom.
A template was made from the existing curved pieces of the VEDAxi. The template was pivoted around the forward end, while adjusting the height at the back. The template was taped in place. Stuff was stared at. Coffee was made. Stuff was stared at again while drinking coffee, this time so long that the tape came loose and allowed the peeeerrrfectly positioned template to come loose. The dog laughed at me. The template was repositioned. The curve was marked. The cuts were made. Stuff was test fit. Coffee was drunk while stuff was stared at. Stuff was waterproofed. More stuff was measured with bricks and shoestrings. Thought to myself “I can get just a little more”. Stuff that had already been waterproofed got cut again. The dog and the cat became friends and laughed at me together. Stuff got waterproofed again. I stared at stuff while stuff dried. I finally tape and clamp the thing back on the PDR. NOW I have a PDR attachment which makes an almost straight run back from the “flat spot” (almost straight because it’s a few degrees tilted up as it goes back, just in a straight line) AND most importantly the transom height is now 14 81/128” (I think I’m remembering that correctly it was soooo important that I can’t admit that I’ve forgotten the actual number).
Time to try this thing out. We (test crew today: me and my two kids) head out to our favorite spot which has a nice dock and the curve of the shoreline is just right with the prevailing wind to really keep the waves down most of the time. We launch the boat. We answer questions about the boat. (Side note to ANYONE who is considering building a PDR: You WILL spend time at the boat ramp answering questions about the boat every time you go to the lake. Every. Single. Time. I’ve loaned the PDR to friends so that they could take their wife/significant other out for a sail. They too, answered questions about the boat at the boat ramp. This is a good thing, unless of course you harbor a strong distaste for hobbies involving camaraderie. But it is in fact a thing. A very time-consuming thing. At the time of writing, I have not yet gone to a boat ramp that had no other people around and had to answer questions, but I fully expect it to happen eventually. Side note complete.) My son and I get in the boat, my daughter is on a tube 52’ 3” behind the boat (ski rope plus carabiner plus 1/2 diameter of the tube). Gimme a break about the tube, we fixed this! It’s going to work flawlessly right? We might as well go big or go back home. Why on earth wouldn’t you just go for broke and make the assumption that you can now pull a kid on a tube behind a $300 8 foot boat with a hull shape changing attachment half-taped, half clamped to the bottom?
Things work pretty well, but slow. Very. Slow. So slow in fact, that the excitement factor of this tubing experience soon has my daughter asking to be dragged (drug, drugged? I’m not nearly as good with grammar as I am with significant digits) through a field of lily pads so that she can collect some to give to Mom when we get home. First and only time that the excitement level of tubing has degenerated to this level of non-awesomeness. My now-driving-the-boat son concedes. At this point, it’s pretty clear that the prop cavitation thing is gone. Just as we intended, this is a by-product of the increased depth of the prop in the water. However, we don’t have nearly enough power to urge the two-up boat plus my daughter, plus the tube, and most recently, plus the lily pads, over the “hump” in the drag curve and plane out. The tube is very near planning, pushing a really big wave which usually happens just before it lets go and planes when we pull it with our big boat. It’s hard to tell for the PDR how near to the edge we are. We mess around a bit, detach the tube, and my daughter joins us in the boat. It’s very controllable, the pitching moment of the original hull shape is gone, the prop cavitation is gone, but we’re still pushing a really big wave at approximately 10mph, and don’t quite have the power to get on plane with three of us on board. This constitutes mild success as we’re going 10mph now (only 1 mph better than the previous 9, but it IS faster), and the lake is now oh so conveniently keeping it’s distance from the transom top.
The kids decide that they want to go swim and jump off the dock. So I let them out, and keeping very near the dock, I flog all 15 of those 1970’s Mail-Order Montgomery Wards horses into action. Action like John Wayne just jumped out o’ a taverns 2nd story window onto Dollor’s back kinda action. (Okay, okay, that was a slight stretch.) Maybe more like your neighbor’s old mare just regained consciousness after a surgical trip to the vet and is still borderline groggy from the anesthesia kind of action. Anyhow, by this time, the wind has shifted and our normally quiet cove is getting beat up with decent waves. (Fine, Fine, I’ll be truthful. They’re really more like growing ripples. At this point please don your 8 foot 15hp colored set of glasses, which will allow you to see ripples as HUGE WAVES for the remainder of the story. Also, we previously failed to do our lawyerly duty and will now remind you to keep your arms, hands, feet, hats, prosthetics and lunch inside the boat for the remainder of the ride.) HUGE WAVES that are making it kinda sketchy for a 16” high boat that’s only 8 feet long with a ludicrous amount of power. BUT IT WORKS! We slog for a second as we start shoving the bow wave and then just like that it lets go and planes! With the weight of just one person and an all up weight of 393lbs (96 hull, 62 outboard, 10 VEDAxi, 36 gas, 14 tools, 175 first mate (there was no captain, if there had been, he surely would have been smart enough to talk us out of this nonsense)). This thing will actually plane out! According to the age old rule of thumb, every 50 pounds of stuff should require about a hp. Based on the success with one person and unsuccess with the two kids on board, I think we’re probably a lot closer to 30 lbs per hp for a planing limit here. But we’re dealing with a very small flat plate area, and it’s a very short flat plate area to boot. Due to the HUGE WAVES (15 horse, 8’ boat colored glasses remember?) the very close proximity to the dock, and keeping an eye on my kids I failed to get a good GPS reading but I’m guessing it was probably somewhere in the 15-17 mph range. There are about 29 1/2 things I wish were a little more controlled for this particular test, but did I mention that IT WORKS! The prototype VEDA xi has now been confirmed as a success. It has achieved its hard-earned rest in the dumpster, and I’m left to return home, stare, drink coffee, and ruminate on a more easily detachable, more permanent version.
In conclusion Shorty, if you have other decent folks fettered with controversial judgment like me wondering if you can plane a PDR with a too-big-outboard, please let my ludicrous experiment be documented somewhere for the entertainment value of the masses. It’s not practical at all, but if you really, really, really want to, an 8’ PDR can indeed be built with a removable attachment that adjusts the hull shape to allow planing powerboat action with a 15hp outboard. With this small of a flat plate area and with this short of a boat, my suspicion is that it takes a lot more horsepower to get it to plane than it would take to keep it on plane once you crest your bow wave. You’re going to have to pay close attention to fore/aft trim. You’re not going to carry your whole family at speed. Your boat will likely beat you half to death in any kind of chop (or maybe she’ll just save herself the trouble and throw you out). Your cat and dog may experience newfound companionship at your expense. But… IT CAN INDEED BE DONE. I now know from personal experience that The Insidious Bufflehead, the smallest of all the diving ducks, can also fly.
