Pete Markantes
New member
The following is a reply to my e-mail to Sam Devlin in which I requested his input to our recent discussion of rocker, porpoising, etc. in the “Cackler Adjustments” thread.
My belief of the hulls having no aft rocker was based upon the bottom and side lofting dimensions being constant from midship to stern on Honker, Snow Goose and Cackler. My conviction was furthered in viewing my Honker hull which was lengthened by 18” in the straight line portion of the hull providing a straight run of greater than 50% of the hull length. My eye is still not able to distinguish any curvature at either keel or chine. In any case, as Sam states, there IS some rocker in the design (barely perceptible though it may be) and I humbly stand corrected. Been wrong before and likely will be again.
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Dear Pete: Wow I just got off the link to the forum website and you guys can really get into it. Perhaps a couple of statements will help all involved in the controversy.
First off all, boat designs are nothing more than a considered response to a series of boat circumstances. Where is the boat going to be run, type of draft of the waters encountered, speed requirement for service duty, amount of occupants desired in vessel, average sea condition of the waters encountered, time of the year (important in the duckboat designs) that the boat is run etc. These and many more questions should be asked and answered before attempting to find the ultimate solution (that’s really an impossibility of course, but we do the best we can).
As most of you really avid hunters know there are really about 5+ boats necessary to adequately cover all the contingency’s that we might find with the average hunter in the average year, from the small sneakbox that fits in the bed of the pickup for those ponds that you can’t get a ramp into, to the mighty garvey design (like the Honker or Little Cod) for those hunts with lots of friends on big water. All of these conditions have appropriate boats for the mission, or you can make do with the best compromise for all things considered. In my designs, each of them have been an answer to what I have found in my own hunting adventures and I would honestly tell you that there will be another half dozen designs at least necessary before I’m done with all this (most of those I already know of the need, just haven’t taken the time to draw up).
Having said that, how do we proceed with recommending or building a boat when we already know that it really won’t answer all our conditions and requirements from start to finish? Answer is make the best estimation that you can for what your needs are, build the darn thing, use it and develop a more experienced and discriminating eye and then rethink the next project. There is only one answer to why so many of you build so many different boats, if it were all about just refinement then I would see you building 6 Black Brants each one a little better than the last. But no, you chose to build a Black Brant, then a Honker, now a Cackler. Either you just really like to build or you see and find a need in each of the designs that answers to conditions that you encounter and dreams that you have for adventures with the boats, and I also assume that you do indeed like to build also!
Okay so let’s talk about rocker! There are really two points to consider with a rocker discussion, the keel or fairbody rocker and the chine rocker. The Keel is fairly obvious with a true profile view of the boat you can trace down the keel or centerline and see if it comes to a straight line in the aftermost 50% of its run to the transom. Same goes true for the chine except that it is a bit more devious to our consideration. But generally if those two features of the boat the Keel profile or the Chine Profile move into a straight line run in their aftermost 50% of run to the transom then you have a boat without rocker. But if those lines bend even slightly then they have some rocker and will exhibit different qualities to the design than the flat runs. You could pick up 6 books on boat design and come up with 6 different speculations as to what the final qualities of these lines might be and what constitutes the definition of true planing performance. In all reality I never would design a duckboat with total true planing capabilities as that is not an elegant solution to what the average duckboat encounters.
Think about it this way, what duckboat goes out on flat calm water with only one person on board in the middle of the summer? Answer is only one that is used outside of its design parameters. Duckboats are overloaded most of their lives, are used in inclement weather most of the time, are run in waters too shallow most of the time, and encounter sea conditions that would turn a normal boats hair white. They also have to maneuver well in tight conditions and have passengers constantly boarding and exiting the boat with lots of weight and gear. We never needed true full planing performance, what we needed was a 3X semi-displacement performance with all those conditions. I.E. they often do have a bit of rocker, they often do need tabs on them to eliminate porpoising, and they are overpowered and overloaded by nature of their intended service duties.
Now for the really tricky part, and this is addressed to all builders of my designs. I never ever liked nor was a proponent of “paint by number boat building”. You can’t at this date buy a kit from me that has a carefully detailed step by step description of how to assemble the boat and I never attempted to hold your hand in every way in this boatbuilding process. It’s a bit complicated as to why I haven’t chosen that approach but the bigger reason is that I have interest in getting more information out in the public then bogging down and just focusing on one or two products. You builders are to a person smart, and you all have the capability of working your way thru this process. And in the end, when you truly end that last stroke of the paint brush or attach the last bit of hardware, you are a member of a very small and exclusive club. You are, my friends, a “Boatbuilder” and you can take pride in being a member of that club. You’ve “breathed life into a pile of materials” and you have created a vessel that can transport you to many, many adventures. By the time you get that boat ready for its first launching you have control of the destiny of that vessel and you are the Master!
Virtually every duckboat that I have launched has been launched without tabs or wedges, I do the first sea trial without them and only add them if necessary. Probably 70% of the boats get them in the long run and perform very well with them. But it’s complicated why they might be necessary and one of the postings in the forum kind of outlines one builder’s solution, rake the engine aft and sometimes raise the engine also. Any of you that have built know that it’s really not a simple matter of clamping on that engine to the stern and taking off, there are adjustments galore to the engine and its interplay with the stern of the boat and height of the bracket etc. is complex. But keep in mind that most of you are using more horsepower than the average boat of that size and most of you are going to operate in conditions that all those tin skiffs were never designed to operate in.
Adding wedges is a fairly simple process with simple blocks of plywood, hardwood, UHMW plastics, or Teflon etc. to the end of the bottom of the boat on both sides equally. A few flathead screws and some bedding compound attach them and seal off the elements from getting into your hull. In most cases I have found about 3/8” of height at the aft edge and about 3-4” in length is just about right. Depends on your boat being built but I would run them at least 12” wide on both sides of the hull. These little devices will put that bow down from porpoising and will live the life of the boat well, don’t make them too complex as they don’t need that and keep it simple. Are my designs lousy for needing them? Depends on who you ask, but I’ve enough data myself and with customers to know that the boats work for their own intended service duty, do it well, and do it for a long time. What more could any of us ask for!
My belief of the hulls having no aft rocker was based upon the bottom and side lofting dimensions being constant from midship to stern on Honker, Snow Goose and Cackler. My conviction was furthered in viewing my Honker hull which was lengthened by 18” in the straight line portion of the hull providing a straight run of greater than 50% of the hull length. My eye is still not able to distinguish any curvature at either keel or chine. In any case, as Sam states, there IS some rocker in the design (barely perceptible though it may be) and I humbly stand corrected. Been wrong before and likely will be again.
----------------------------
Dear Pete: Wow I just got off the link to the forum website and you guys can really get into it. Perhaps a couple of statements will help all involved in the controversy.
First off all, boat designs are nothing more than a considered response to a series of boat circumstances. Where is the boat going to be run, type of draft of the waters encountered, speed requirement for service duty, amount of occupants desired in vessel, average sea condition of the waters encountered, time of the year (important in the duckboat designs) that the boat is run etc. These and many more questions should be asked and answered before attempting to find the ultimate solution (that’s really an impossibility of course, but we do the best we can).
As most of you really avid hunters know there are really about 5+ boats necessary to adequately cover all the contingency’s that we might find with the average hunter in the average year, from the small sneakbox that fits in the bed of the pickup for those ponds that you can’t get a ramp into, to the mighty garvey design (like the Honker or Little Cod) for those hunts with lots of friends on big water. All of these conditions have appropriate boats for the mission, or you can make do with the best compromise for all things considered. In my designs, each of them have been an answer to what I have found in my own hunting adventures and I would honestly tell you that there will be another half dozen designs at least necessary before I’m done with all this (most of those I already know of the need, just haven’t taken the time to draw up).
Having said that, how do we proceed with recommending or building a boat when we already know that it really won’t answer all our conditions and requirements from start to finish? Answer is make the best estimation that you can for what your needs are, build the darn thing, use it and develop a more experienced and discriminating eye and then rethink the next project. There is only one answer to why so many of you build so many different boats, if it were all about just refinement then I would see you building 6 Black Brants each one a little better than the last. But no, you chose to build a Black Brant, then a Honker, now a Cackler. Either you just really like to build or you see and find a need in each of the designs that answers to conditions that you encounter and dreams that you have for adventures with the boats, and I also assume that you do indeed like to build also!
Okay so let’s talk about rocker! There are really two points to consider with a rocker discussion, the keel or fairbody rocker and the chine rocker. The Keel is fairly obvious with a true profile view of the boat you can trace down the keel or centerline and see if it comes to a straight line in the aftermost 50% of its run to the transom. Same goes true for the chine except that it is a bit more devious to our consideration. But generally if those two features of the boat the Keel profile or the Chine Profile move into a straight line run in their aftermost 50% of run to the transom then you have a boat without rocker. But if those lines bend even slightly then they have some rocker and will exhibit different qualities to the design than the flat runs. You could pick up 6 books on boat design and come up with 6 different speculations as to what the final qualities of these lines might be and what constitutes the definition of true planing performance. In all reality I never would design a duckboat with total true planing capabilities as that is not an elegant solution to what the average duckboat encounters.
Think about it this way, what duckboat goes out on flat calm water with only one person on board in the middle of the summer? Answer is only one that is used outside of its design parameters. Duckboats are overloaded most of their lives, are used in inclement weather most of the time, are run in waters too shallow most of the time, and encounter sea conditions that would turn a normal boats hair white. They also have to maneuver well in tight conditions and have passengers constantly boarding and exiting the boat with lots of weight and gear. We never needed true full planing performance, what we needed was a 3X semi-displacement performance with all those conditions. I.E. they often do have a bit of rocker, they often do need tabs on them to eliminate porpoising, and they are overpowered and overloaded by nature of their intended service duties.
Now for the really tricky part, and this is addressed to all builders of my designs. I never ever liked nor was a proponent of “paint by number boat building”. You can’t at this date buy a kit from me that has a carefully detailed step by step description of how to assemble the boat and I never attempted to hold your hand in every way in this boatbuilding process. It’s a bit complicated as to why I haven’t chosen that approach but the bigger reason is that I have interest in getting more information out in the public then bogging down and just focusing on one or two products. You builders are to a person smart, and you all have the capability of working your way thru this process. And in the end, when you truly end that last stroke of the paint brush or attach the last bit of hardware, you are a member of a very small and exclusive club. You are, my friends, a “Boatbuilder” and you can take pride in being a member of that club. You’ve “breathed life into a pile of materials” and you have created a vessel that can transport you to many, many adventures. By the time you get that boat ready for its first launching you have control of the destiny of that vessel and you are the Master!
Virtually every duckboat that I have launched has been launched without tabs or wedges, I do the first sea trial without them and only add them if necessary. Probably 70% of the boats get them in the long run and perform very well with them. But it’s complicated why they might be necessary and one of the postings in the forum kind of outlines one builder’s solution, rake the engine aft and sometimes raise the engine also. Any of you that have built know that it’s really not a simple matter of clamping on that engine to the stern and taking off, there are adjustments galore to the engine and its interplay with the stern of the boat and height of the bracket etc. is complex. But keep in mind that most of you are using more horsepower than the average boat of that size and most of you are going to operate in conditions that all those tin skiffs were never designed to operate in.
Adding wedges is a fairly simple process with simple blocks of plywood, hardwood, UHMW plastics, or Teflon etc. to the end of the bottom of the boat on both sides equally. A few flathead screws and some bedding compound attach them and seal off the elements from getting into your hull. In most cases I have found about 3/8” of height at the aft edge and about 3-4” in length is just about right. Depends on your boat being built but I would run them at least 12” wide on both sides of the hull. These little devices will put that bow down from porpoising and will live the life of the boat well, don’t make them too complex as they don’t need that and keep it simple. Are my designs lousy for needing them? Depends on who you ask, but I’ve enough data myself and with customers to know that the boats work for their own intended service duty, do it well, and do it for a long time. What more could any of us ask for!
