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Author Topic:   SPORT 13: Adding Set-Back Bracket

sixmile posted 08-19-2007 11:16 AM ET (US)
I have a SPORT 13 with a 40-HP Evinrude. Since [the 13-foot Boston Whaler boat is] so short they all love to porpoise. They also don't like a whole lot of [positive] trim either. I would think by setting the motor further back off the transom that would possibly cut down on the proposing and may allow for [positive] more trim. I have never seen [a 13-foot Boston Whaler boat with an outboad motor set back bracket]. Curious if anyone has tried [adding a set back bracket to a 13-foot Boston Whaler boat] and what resulted. Thanks, Ed
jimh posted 08-20-2007 05:21 AM ET (US)
I believe that many people have added a set back bracket to a Boston Whaler 13-footer with a 15-inch transom in order to use a 20-inch shaft motor. The overall enhancing effect of adding a set back bracket has to balanced against the detracting effect of its added weight.
I recently saw a 13-foot Whaler with a 15-inch transom that had been fitted with a 40-HP Suzuki motor. It looked like it was already a bit stern heavy, and I wondered if adding a set back bracket would be beneficial as the additional weight would not be welcomed.
In the CETACEA collection there are many photographs showing smaller Boston Whaler boats with set back brackets. For example, you can see the work of Clark Roberts in CETACEA PAGE 28:

http://continuouswave.com/whaler/cetacea/cetaceaPage28.html
Also see Carl Neusel's fine work in
http://continuouswave.com/whaler/cetacea/cetaceaPage56.html
Tohsgib posted 08-20-2007 11:23 AM ET (US)
I have a 81 13 with a 94 40 Rude on a 8" setback and she still porpoises like hell. I picked up some speed and dropped a few inches in draft is all.
sixmile posted 08-20-2007 06:29 PM ET (US)
The problem I encountered with mine was trying to determine setup. I bought this second hand and repowered it. Not being familiar with the hull I found it tough at first to dial it in. The engine was originally mounted on the second hole up but it would porpoise pretty bad and the tilt and trim made little to no difference. I then dropped it down on the transom and that helped the porposing but again it did not like much + trim. I then put a Doel fin on which helped but finally I came across a stabilizer plate from Bob’s machine shop that actually worked best. Then once I fixed my tachometer the original 15-inch prop I had was turning way to many R.P.M.’s so I finally ended up with a 19 inch. Quite a big prop for a relatively small motor. So now I am wondering if setting the motor back will help the overall performance? Although I love this little boat is has been quite the learning experience. Thanks, Ed
Tohsgib posted 08-21-2007 12:24 PM ET (US)
I run a 17" SS Rapture and I can get about 5600 so no biggie beng you can't run that but a moment. I thought about a 19 but holeshot on he 17 is kinda slow with weight plus I am not spending the $$. I get mid 37's on a daring day.
sixmile posted 08-21-2007 04:16 PM ET (US)
If you are looking for a little more muscle out of your 40-Rude here is a trick I don't know if you are familiar with the carburetion on your E-Rude 40 but the only difference between 1989 to present 40 and 50 hp (2 cyl.) motors are the carburetors. The 40’ies had the small venturies and the 50ies had the large ones. Not only will you gain horsepower but also your motor will idle much better. Before I changed my carburetors my 40 would turn a 17-inch prop around 5500 to 5600. After the change it was pushing that same prop almost to 6000. That’s why I am able to run a 19-inch prop and my hole shot is just as strong as with the 17. I just swapped carburetors off a 50 and the only thing I paid for were the kits. Ed
Tohsgib posted 08-22-2007 12:22 PM ET (US)
Last thing I need on this pig is more speed. When/if she ever goes I will actually put a 25-30 4 stroke on it.
sixmile posted 08-24-2007 07:38 PM ET (US)
My first 4-stroke motor I purchased was a 06 Suzuki 2.5 h.p. Great little motor. I liked it so much I bought a 70 for my pontoon. No problems starts right up and is extremely quite. I actually hear the water over the engine. Plus I almost doubled my gas mileage. Anyway I think Suzuki makes a 25 horsepower that is a V-Twin engine configuration similar to a Harley Davidson. I read reviews and nothing but praise for this motor. They also noted that when compared to the other 4 stroke makers with similar hp the Suzuki out preformed them all. Basically a 25 Suzuki outperformed a 30 Yamaha and was a little cheaper to get into. I like Suzuki because they offer a six-year warranty, which I think, is the best in the industry. FYI Ed
Binkie posted 08-25-2007 03:55 PM ET (US)
A set back bracket will never eliminate porpoising, especially on a 13 footer. It only increases the lever action and might make the boat porpoise more. It does not make the boat ride like a longer boat, because there is not extra length bottom to support the set back. I can`t prove this with formulas, as I`m not really an ingineer, like some here, but only from experience and common sense. One approach to eliminate porpoising which I have never seen on a 13 footer is to build a bait box on each side of the motor attached to the transom. Make them say, 12 to 16 inches long and mount them 1/2" higher than the bottom. You have a lid on the top to scoop out your live bait, and drill some holes in the back to let the water out when on plane. The holes have to be high enough, so all the water doesn`t drain and kill the bait when on plane for a long time. these could be designed so as to fit in with the design of the boat. It will give the boat more planing surface, and in fact make the boat ride like a longer boat with the motor sitting in a well. They were used on many fishing boats in the `70`s.
My 13 footer doesn`t porpoise at all. I`m running a 135lb `58 Evinrude Lark (restored) It doesn`t have t-n-t of course, motor is set at vertical. I can`t kick it out any more. I have a custom mahogany interior with a larger and higher side console (about 45 lb.) The interior is moved 6" forward. The rear thwart is mounted on top of the seat clamps, and 2, 6 gallon tanks and the battery are under the seat. Behind the rear seat from the seat to the splash bulkhead is a teak casting platform(35 lbs)with space for storage under. The boat will jump up on plane and run in what seems like perfect trim, and is happy running in 1`chop wide open, about 25 mph. I don`t know how to post pics to the site yet.
rich
Tohsgib posted 08-27-2007 11:10 AM ET (US)
Six...I have owned 4 suzukis since 1981 and loved them all. My 17 had a 70 4 stre and my 19 Revenge currently runs a 115. If/when I d repower it will most likely be another Suzuki unless I score a deal on something else.
Binkie posted 08-27-2007 12:45 PM ET (US)
I`m with Tohs on the Suzuki thing, When I tire of my "classic" motor, I`ll go with the V-twin 25 hp Suzuki. My only regret is they only come on short shaft towers, unless you get a tiller model. I wonder if I could buy the parts and convert it myself?
Rich
exSmoker posted 08-28-2007 10:06 PM ET (US)
My first Post:
I finally just last week took out my 1980, 13 footer with a 2008 40 ETEC and a 5 1/2 inch CMC jack plate. I mounted the plate all the way up and adjusted all the way up. I put a SS Viper prop @ 13 7/8" x 17" pitch. I had the 12 gallon tank (full) up front right behind the battery. I moved the bench and console forward 4 inches and brought my 300 lb friend.
WOW! what a ride. No GPS yet.
With the hole shot trimmed down for about 3 seconds trimmed up gradually till 5200 RPM's were reached it will porpoise a little with glass or chop. But, the power tilt can be dialed in losing some RPM's but a great smoooth ride.
I wish I knew how to show pics of the exSmoker.
This has been a great little project boat.
Tohsgib posted 08-29-2007 11:22 AM ET (US)
I was just going to start a post seeing if anyone has put a 40 E-tec on a 13...get some GPS numbes and maybe a pic from the side showing how it sits in the water please. Is 240+lbs of engine a problem especially with a plate?
exSmoker posted 08-29-2007 04:24 PM ET (US)
When you do mount your plate, mount it a maximum height about 3/4" from green line. You will need to adjust plate all the way up. When I took mine out the first time at middle condition the bottom of jack plate was cupping the water. But now it has about 2 inches clearance.
No cavitation. I will take some profile water shots this weekend and post.
http://s230.photobucket.com/albums/ee224/exsmoker/
sixmile posted 09-01-2007 01:23 PM ET (US)
Ok gents, Problem solved. I told one of my friends who happens to be a marine mechanic about the proposing problem with this rig. Bottom-line they all porpoise easy due to the short length and power to weight ratio. And although a jackplate might help slightly by allowing to get a little more + trim and speed it would likely make porposing even worse. He recommended Smart tabs. That was the last thing I wanted to hear due to the price and yet another thing to adjust. I did not realize these are trim plates that have a nitrogen filled shock absorber that adjusts to the water pressure automatically. I went to Boat Owners world and picked up a set for $139.00 no tax-free shipping. It took me about a half hour to mount them and it was quite easy. So without the tabs I was using an 11.75/19 prop. It was slow to plane and turned 5400 wide open. When wide open it would porpoise and sometimes fall of its pad. With the tabs it planned almost immediately and the bow did not stand straight up before it came down on plane. It also allowed the motor to trim up higher resulting in about 200 more rpm's. I have tried my damnest to get it to porpoise since but it just wont. When running wot it has a slightly higher bow rise but has not fell of its pad. I gained about 3-4 M.P.H. on top end. Ed
Tohsgib posted 09-04-2007 11:32 AM ET (US)
Did you try a doel fin before? Many swear by them, I have just not tried one yet on this hull but am going to.
WellFairFisherman posted 09-04-2007 07:33 PM ET (US)
Can I please get some more info on the smart tabs you chose and possibly some pics of your install....
I did some thinking about these and thought they would be clear of the water when on plane due to the hook in the hull...
Also I do quite a bit of backing down while fishing and didn't want to lose anymore of my reverse manueverability.....Thanks

PeteB88 posted 09-05-2007 01:17 AM ET (US)
MY 13 will porpoise when I run it solo and trimmed (by pin on motor) mid hole or second from bottom (less) and not at all when motor is full down (pin set). IN that configuration it really has a reverse attitude (slight) and is really deep.
I generally run one or two passengers and lots of gear but load (w/ me especially) is more stern than forward. I set the pin at second from bottom.
In that configuration I can get the boat to porpoise when I am solo. No doubt about it. I have tried several things short of spending a bunch of money and drilling a bunch of holes.
Remedy? If it porpoises I hit the throttle and the oscillations general go away. If not, I simply lean forward a bit, sit in center and sort of lean forward while steering and working throttle, butt on the seat. IT is amazing how little change of weight and balance had a huge impact. Push that throttle forward and it might work but be careful.
I have considered a couple of 25 pound shotgun shot bags up in the forward locker. That's about the weight, w/ some misc stuff, of our STd Poodle Lou RIP a couple of months ago.
Tohsgib posted 09-05-2007 11:59 AM ET (US)
Have you priced Shotgun lead recently? Might be better off buying sinkers/dipsies at garage sales.
Binkie posted 09-05-2007 08:33 PM ET (US)
Pete try this;
Unscrew your entire mahogany interior, and move the whole thing forward 6 inches. then mount your rear thwart on top of the seat clamps instead of underneath. Now you have room to put two six gallon tanks and your battery under the seat. Your steering cable will probably work unless your using cable and pulley. Works wonders. No need to drill new holes until you test it and see if you like it. I`ll send pics of mine.
I set the pin in the vertical position, and boat won`t porpoise at all. Will run flat and smooth over a 1 foot chop.
Rich
Tom Hemphill posted 09-05-2007 09:50 PM ET (US)
The modification Binkie suggests was discussed in more detail at http://continuouswave.com/ubb/Forum4/HTML/005122.html .
As to a source of lead weights, for SCUBA diving I have used both lead shot in mesh bags and cast lead weights. Both are expensive if bought from a dive shop. The former is less likely to damage a boat, but I actually prefer the cast weights for diving. Many of them I made myself using molds designed for this purpose, obtaining the lead from tire shops who are more than happy to give away old tire weights. Please don't breathe the fumes if you choose to cast lead weights!
WellFairFisherman posted 09-28-2007 12:18 AM ET (US)
Any update on the performance of smart tabs on the 13 foot whaler hull??.....
an86carrera posted 09-28-2007 12:28 AM ET (US)
Tohs,
I have a Doel Thing, YOU can have it. Yes I know they work but, I always add more HP instead:-]
Len

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Author	Topic: SPORT 13: Adding Set-Back Bracket
sixmile	posted 08-19-2007 11:16 AM ET (US) I have a SPORT 13 with a 40-HP Evinrude. Since [the 13-foot Boston Whaler boat is] so short they all love to porpoise. They also don't like a whole lot of [positive] trim either. I would think by setting the motor further back off the transom that would possibly cut down on the proposing and may allow for [positive] more trim. I have never seen [a 13-foot Boston Whaler boat with an outboad motor set back bracket]. Curious if anyone has tried [adding a set back bracket to a 13-foot Boston Whaler boat] and what resulted. Thanks, Ed
jimh	posted 08-20-2007 05:21 AM ET (US) I believe that many people have added a set back bracket to a Boston Whaler 13-footer with a 15-inch transom in order to use a 20-inch shaft motor. The overall enhancing effect of adding a set back bracket has to balanced against the detracting effect of its added weight. I recently saw a 13-foot Whaler with a 15-inch transom that had been fitted with a 40-HP Suzuki motor. It looked like it was already a bit stern heavy, and I wondered if adding a set back bracket would be beneficial as the additional weight would not be welcomed. In the CETACEA collection there are many photographs showing smaller Boston Whaler boats with set back brackets. For example, you can see the work of Clark Roberts in CETACEA PAGE 28: http://continuouswave.com/whaler/cetacea/cetaceaPage28.html Also see Carl Neusel's fine work in http://continuouswave.com/whaler/cetacea/cetaceaPage56.html
Tohsgib	posted 08-20-2007 11:23 AM ET (US) I have a 81 13 with a 94 40 Rude on a 8" setback and she still porpoises like hell. I picked up some speed and dropped a few inches in draft is all.
sixmile	posted 08-20-2007 06:29 PM ET (US) The problem I encountered with mine was trying to determine setup. I bought this second hand and repowered it. Not being familiar with the hull I found it tough at first to dial it in. The engine was originally mounted on the second hole up but it would porpoise pretty bad and the tilt and trim made little to no difference. I then dropped it down on the transom and that helped the porposing but again it did not like much + trim. I then put a Doel fin on which helped but finally I came across a stabilizer plate from Bob’s machine shop that actually worked best. Then once I fixed my tachometer the original 15-inch prop I had was turning way to many R.P.M.’s so I finally ended up with a 19 inch. Quite a big prop for a relatively small motor. So now I am wondering if setting the motor back will help the overall performance? Although I love this little boat is has been quite the learning experience. Thanks, Ed
Tohsgib	posted 08-21-2007 12:24 PM ET (US) I run a 17" SS Rapture and I can get about 5600 so no biggie beng you can't run that but a moment. I thought about a 19 but holeshot on he 17 is kinda slow with weight plus I am not spending the $$. I get mid 37's on a daring day.
sixmile	posted 08-21-2007 04:16 PM ET (US) If you are looking for a little more muscle out of your 40-Rude here is a trick I don't know if you are familiar with the carburetion on your E-Rude 40 but the only difference between 1989 to present 40 and 50 hp (2 cyl.) motors are the carburetors. The 40’ies had the small venturies and the 50ies had the large ones. Not only will you gain horsepower but also your motor will idle much better. Before I changed my carburetors my 40 would turn a 17-inch prop around 5500 to 5600. After the change it was pushing that same prop almost to 6000. That’s why I am able to run a 19-inch prop and my hole shot is just as strong as with the 17. I just swapped carburetors off a 50 and the only thing I paid for were the kits. Ed
Tohsgib	posted 08-22-2007 12:22 PM ET (US) Last thing I need on this pig is more speed. When/if she ever goes I will actually put a 25-30 4 stroke on it.
sixmile	posted 08-24-2007 07:38 PM ET (US) My first 4-stroke motor I purchased was a 06 Suzuki 2.5 h.p. Great little motor. I liked it so much I bought a 70 for my pontoon. No problems starts right up and is extremely quite. I actually hear the water over the engine. Plus I almost doubled my gas mileage. Anyway I think Suzuki makes a 25 horsepower that is a V-Twin engine configuration similar to a Harley Davidson. I read reviews and nothing but praise for this motor. They also noted that when compared to the other 4 stroke makers with similar hp the Suzuki out preformed them all. Basically a 25 Suzuki outperformed a 30 Yamaha and was a little cheaper to get into. I like Suzuki because they offer a six-year warranty, which I think, is the best in the industry. FYI Ed
Binkie	posted 08-25-2007 03:55 PM ET (US) A set back bracket will never eliminate porpoising, especially on a 13 footer. It only increases the lever action and might make the boat porpoise more. It does not make the boat ride like a longer boat, because there is not extra length bottom to support the set back. I can`t prove this with formulas, as I`m not really an ingineer, like some here, but only from experience and common sense. One approach to eliminate porpoising which I have never seen on a 13 footer is to build a bait box on each side of the motor attached to the transom. Make them say, 12 to 16 inches long and mount them 1/2" higher than the bottom. You have a lid on the top to scoop out your live bait, and drill some holes in the back to let the water out when on plane. The holes have to be high enough, so all the water doesn`t drain and kill the bait when on plane for a long time. these could be designed so as to fit in with the design of the boat. It will give the boat more planing surface, and in fact make the boat ride like a longer boat with the motor sitting in a well. They were used on many fishing boats in the `70`s. My 13 footer doesn`t porpoise at all. I`m running a 135lb `58 Evinrude Lark (restored) It doesn`t have t-n-t of course, motor is set at vertical. I can`t kick it out any more. I have a custom mahogany interior with a larger and higher side console (about 45 lb.) The interior is moved 6" forward. The rear thwart is mounted on top of the seat clamps, and 2, 6 gallon tanks and the battery are under the seat. Behind the rear seat from the seat to the splash bulkhead is a teak casting platform(35 lbs)with space for storage under. The boat will jump up on plane and run in what seems like perfect trim, and is happy running in 1`chop wide open, about 25 mph. I don`t know how to post pics to the site yet. rich
Tohsgib	posted 08-27-2007 11:10 AM ET (US) Six...I have owned 4 suzukis since 1981 and loved them all. My 17 had a 70 4 stre and my 19 Revenge currently runs a 115. If/when I d repower it will most likely be another Suzuki unless I score a deal on something else.
Binkie	posted 08-27-2007 12:45 PM ET (US) I`m with Tohs on the Suzuki thing, When I tire of my "classic" motor, I`ll go with the V-twin 25 hp Suzuki. My only regret is they only come on short shaft towers, unless you get a tiller model. I wonder if I could buy the parts and convert it myself? Rich
exSmoker	posted 08-28-2007 10:06 PM ET (US) My first Post: I finally just last week took out my 1980, 13 footer with a 2008 40 ETEC and a 5 1/2 inch CMC jack plate. I mounted the plate all the way up and adjusted all the way up. I put a SS Viper prop @ 13 7/8" x 17" pitch. I had the 12 gallon tank (full) up front right behind the battery. I moved the bench and console forward 4 inches and brought my 300 lb friend. WOW! what a ride. No GPS yet. With the hole shot trimmed down for about 3 seconds trimmed up gradually till 5200 RPM's were reached it will porpoise a little with glass or chop. But, the power tilt can be dialed in losing some RPM's but a great smoooth ride. I wish I knew how to show pics of the exSmoker. This has been a great little project boat.
Tohsgib	posted 08-29-2007 11:22 AM ET (US) I was just going to start a post seeing if anyone has put a 40 E-tec on a 13...get some GPS numbes and maybe a pic from the side showing how it sits in the water please. Is 240+lbs of engine a problem especially with a plate?
exSmoker	posted 08-29-2007 04:24 PM ET (US) When you do mount your plate, mount it a maximum height about 3/4" from green line. You will need to adjust plate all the way up. When I took mine out the first time at middle condition the bottom of jack plate was cupping the water. But now it has about 2 inches clearance. No cavitation. I will take some profile water shots this weekend and post. http://s230.photobucket.com/albums/ee224/exsmoker/
sixmile	posted 09-01-2007 01:23 PM ET (US) Ok gents, Problem solved. I told one of my friends who happens to be a marine mechanic about the proposing problem with this rig. Bottom-line they all porpoise easy due to the short length and power to weight ratio. And although a jackplate might help slightly by allowing to get a little more + trim and speed it would likely make porposing even worse. He recommended Smart tabs. That was the last thing I wanted to hear due to the price and yet another thing to adjust. I did not realize these are trim plates that have a nitrogen filled shock absorber that adjusts to the water pressure automatically. I went to Boat Owners world and picked up a set for $139.00 no tax-free shipping. It took me about a half hour to mount them and it was quite easy. So without the tabs I was using an 11.75/19 prop. It was slow to plane and turned 5400 wide open. When wide open it would porpoise and sometimes fall of its pad. With the tabs it planned almost immediately and the bow did not stand straight up before it came down on plane. It also allowed the motor to trim up higher resulting in about 200 more rpm's. I have tried my damnest to get it to porpoise since but it just wont. When running wot it has a slightly higher bow rise but has not fell of its pad. I gained about 3-4 M.P.H. on top end. Ed
Tohsgib	posted 09-04-2007 11:32 AM ET (US) Did you try a doel fin before? Many swear by them, I have just not tried one yet on this hull but am going to.
WellFairFisherman	posted 09-04-2007 07:33 PM ET (US) Can I please get some more info on the smart tabs you chose and possibly some pics of your install.... I did some thinking about these and thought they would be clear of the water when on plane due to the hook in the hull... Also I do quite a bit of backing down while fishing and didn't want to lose anymore of my reverse manueverability.....Thanks
PeteB88	posted 09-05-2007 01:17 AM ET (US) MY 13 will porpoise when I run it solo and trimmed (by pin on motor) mid hole or second from bottom (less) and not at all when motor is full down (pin set). IN that configuration it really has a reverse attitude (slight) and is really deep. I generally run one or two passengers and lots of gear but load (w/ me especially) is more stern than forward. I set the pin at second from bottom. In that configuration I can get the boat to porpoise when I am solo. No doubt about it. I have tried several things short of spending a bunch of money and drilling a bunch of holes. Remedy? If it porpoises I hit the throttle and the oscillations general go away. If not, I simply lean forward a bit, sit in center and sort of lean forward while steering and working throttle, butt on the seat. IT is amazing how little change of weight and balance had a huge impact. Push that throttle forward and it might work but be careful. I have considered a couple of 25 pound shotgun shot bags up in the forward locker. That's about the weight, w/ some misc stuff, of our STd Poodle Lou RIP a couple of months ago.
Tohsgib	posted 09-05-2007 11:59 AM ET (US) Have you priced Shotgun lead recently? Might be better off buying sinkers/dipsies at garage sales.
Binkie	posted 09-05-2007 08:33 PM ET (US) Pete try this; Unscrew your entire mahogany interior, and move the whole thing forward 6 inches. then mount your rear thwart on top of the seat clamps instead of underneath. Now you have room to put two six gallon tanks and your battery under the seat. Your steering cable will probably work unless your using cable and pulley. Works wonders. No need to drill new holes until you test it and see if you like it. I`ll send pics of mine. I set the pin in the vertical position, and boat won`t porpoise at all. Will run flat and smooth over a 1 foot chop. Rich
Tom Hemphill	posted 09-05-2007 09:50 PM ET (US) The modification Binkie suggests was discussed in more detail at http://continuouswave.com/ubb/Forum4/HTML/005122.html . As to a source of lead weights, for SCUBA diving I have used both lead shot in mesh bags and cast lead weights. Both are expensive if bought from a dive shop. The former is less likely to damage a boat, but I actually prefer the cast weights for diving. Many of them I made myself using molds designed for this purpose, obtaining the lead from tire shops who are more than happy to give away old tire weights. Please don't breathe the fumes if you choose to cast lead weights!
WellFairFisherman	posted 09-28-2007 12:18 AM ET (US) Any update on the performance of smart tabs on the 13 foot whaler hull??.....
an86carrera	posted 09-28-2007 12:28 AM ET (US) Tohs, I have a Doel Thing, YOU can have it. Yes I know they work but, I always add more HP instead:-] Len