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Author Topic:   13-footer: Yamaha Jet Outboard

Riptide23WA posted 01-02-2007 01:19 AM ET (US)
While thumbing thru an old 1997 Yamaha brochure the other night, I got to thinking about the possiblity of plopping a small Yamaha jet outboard on the back of my project 13-foot classic Boston Whaler boat. [Yamaha] made a 35- and 28-HP. The weight looks a little much at 170 and 158 pounds, but I plan to mount the gas tank amidships, so that might counteract it a bit.
I want to make this boat a shallow water fishing boat, and thought this might fit the bill. Anybody have experience with such a combo?
Pat
anthonylisske posted 01-02-2007 09:05 AM ET (US)
One thing to consider is that there is approx. a 20% power loss with the jets. (i.e. - 100HP prop = 80hp jet)
My Brother lives on the shore of a large salt water estuary and I was thinking what you where thinking, but in the end it was much more expensive, and much more hassle than a proped motor.
runpasthefence posted 01-02-2007 09:37 AM ET (US)
There was an outboard jet lower unit attachment on sale on Ebay a few months back that would fit my Yamaha for my 15' CC. I did some research to determine if it would be a smart buy.
The amount of water needed to run a boat with a jet outboard is amazing. However, what kept me from buying that unit was the fact that although you can run in 3-4" of water, you still would need a significant amount of depth to get back on plane once you stop.
I figured there aren't many situations (for me) when I would encounter that shallow of water then end up in deep enough water to re-plane.
The Judge posted 01-02-2007 01:51 PM ET (US)
Depends on what type of bottom you are running across. Rocky, then jets are great and maybe even necessary. Mud, you will suck it up in a heartbeat. The new jets are jet rated hp. That 35 is probably a 50hp prop engine so 35hp, jet. 28 is probably a 40, hence why they are expensive. Main problem with jets is they do not like to go slow. If you are the type to run 5000 rpms all day, jets are good. If you are like me and like to loaf along at 22mph, you will probably find jets a tad finicky. Try going slow cruise on a jetski.
Teak Oil posted 01-02-2007 03:32 PM ET (US)
Also this may not be a good option if you are going into shallow weedy areas. Spending all day pulling weeds out of the impeller over and over again is not relaxing
PeteB88 posted 01-02-2007 09:52 PM ET (US)
Probably not the right thing to do - listen to the advice. Outboard jets were designed for Western rivers way back, rocky, some sand, little weed problems - to push boats through fast water, shallow and rapids. I can run my 13 in very little water w/ prop - into mud, weeds etc when fishing with top waters. Jet would be impossible and you lose way too much power. As far as I'm concerned jet pumps are indicated for places that would shred the blades off a propeller.
Riptide23WA posted 01-03-2007 12:12 AM ET (US)
Sheesh, it all sounds like sage advice. I am aiming to fish the sandy flats near where I live... hadn't thought about the sand/mud factor. And the low rpm performance is a good point too.
This has been a question I've had for awhile. I should have asked a long time ago, and quit wasting brain power on it...
Thanks to all. Pat
PeteB88 posted 01-03-2007 10:27 AM ET (US)
We got your back Riptide, that's what this is all about. My fishin pal had to have a jet boat set up for river fishing and insisted that a 25 Merc w/ pump would be perfect. Ya right. He goes over 225 lbs and so do his friends. You probably guessed it - joke, not enough power and in current that = dangerous.
Enjoy and Happy New year.
Riptide23WA posted 01-03-2007 10:34 PM ET (US)
Thanks Pete. I have often wondered about marrying an OMC jet from a Rage or other jet boat, to a flats boat hull. I think one would end up with a low profile stern/fishing platform, with no OB to tilt up, or jackplate up. Wouldn't need a poling platform over the engine either.
I guess I know why it hasn't been done now...
Pat
logjam posted 01-09-2007 05:09 PM ET (US)
I wouldn't totally give up on the idea of a flats jet boat but the idea of trying to make one out of a whaler is not the best idea. The hull design and shape are not the problem. It will work I have experimented some with it on an 11 and a 17; both worked but were underpowered carrying a load. The problem is the weight. In order to make a jet boat work well you need to keep it light or throw a lot of horsepower and a big jet at it. Setting up a whaler as a flats boat is kind of defeating the purpose of having a flats boat. Compared to a light boat of the same size it would be hard to pole, take two or three times as much water off the step and be hard to get unstuck when you make a mistake.
I don't know what you are up against on your flats but I have used both outboard jets and inboard jets on The Copper, Stikine, and Yukon Deltas as well as the connected river systems. All three systems have lots of sand, mud and glacial silt as well as rock and gravel higher in the river systems. It seemed that the only places that caused any real problems were clogging the grates with smll rocks or large gravel when trying to start in shallow water and trash running in some weed beds.
By far the most fun I had was with a 17'Welded aluminum skiff made by Svendson Marine in Wrangell. The outboard jet was recessed into a ramped tunnel and the shallow water performance was truly amazing. It seemed that if you saw water you could go as long as you didn't stop. Getting going in shallow water was usually not a problem if the boat would float unless trying to start in gravel or small rocks.
On the Copper River Delta 1/2 of the commercial fleet uses jet drives in 26'-32' inboard bowpickers. We are talking sand, mud, and silt in shallow sloughs as well as surf where the big gulf of alaska swell hits the shallow waters of the Delta. In this environment the jet rigs are far superior to anything else. In addition the maintenance is much less than outdrives which tend to get destroyed in the harsh working conditions. The jets will run efficiently in shallow water but the efficiency starts dropping in deep water and cavitation can be a problem in rough water. Everyone tries to run in shallow water to pick up speed and save fuel. Most try to deliver fish to tenders in an effort to keep boats lighter but still these boats are hauling far more ice, fish, and gear than the average sportfishing vessel. If the concept of a jet drive didn't work the commercial fleet would not be using them.
I think that jet units often get a bad rap from guys that are trying to use an improperly sized, misadjusted, or worn out impeller; Also from guys asking too much from an underpowered engine or too small a jet.
If you did decide to try a jet on your 13 you will need to put a bracket on the transom to get the jet to the right level. The 50hp powerhead would probably be just about right but don't expect it to run with a light jet boat with a ramped tunnel.
Greg
contender posted 01-10-2007 10:20 PM ET (US)
If jets are so good why dont you see more of them, get the prop...good luck
logjam posted 01-10-2007 11:17 PM ET (US)
I have to agree. If I were powering a 13' whaler I would use a prop. If I wanted fuel efficiency at cruise in water over a foot or two I would use a prop. If I wanted to run in the same depth of water that people use boogie boards to keep from crossing dangerous surf or go through surf without leaving a lower unit or outdrive behind I would use a jet and a boat designed for the purpose.
My pro jet comments are not to encourage riptide to use a jet on a whaler. I would in fact discourage that. My pro jet comments are to encourage him to keep thinking outside of the Boston Whaler Box if he truly needs shallow water or surf performance and not to rule out a jet because of all the negative comments. I would try one in a similar area of use before buying one.
I also encourage Riptide to keep thinking about all of his ideas. None of it is wasted brain power and someone has to be the first. It's only time and money!
Riptide23WA posted 01-11-2007 11:18 PM ET (US)
logjam, thanks for the insight. I have always been curious about jet performance, as my only experience has been aboard PWC's. I was thinking about the shallow water performance mainly, not top speed, or surfing, or anything else. You bring up a good point in that the 13 hull, with no tunnel, isn't really designed for a jet, although somebody posted some pix of a jet prototype from a long time ago...
Still, were I to come across a jet OB cheap, I'd still wanna try it out. Ain't no lesson learned so well as the one you learned the hard way! '-)
Anyway, the 13 may not make the best flats boat, but since I have two of them, I thought I'd set one up as a pocket fishing platform.
Thanks again.
Pat
logjam posted 01-12-2007 08:01 AM ET (US)
Pat,
I think I gave the false impression that the jet actually rides in a tunnel like the prototype whaler that you mentioned. The ramp just allows water to flow up to the foot of the jet which is riding several inches higher than the bottom of the transom to keep it from hanging up on the sea floor.
People ran jets for a long time before they started building ramps into the bottom of hulls to protect outboard jets. Without the ramp the jet foot has to hang down at least to the bottom of the transom where it is more prone to dragging or sucking up debris.
Again I hate to see you put together a package that won't perform the way that it should. I'll always remember hanging up the foot of an outboard jet powered 11' in a channel with a sand bottom on a falling tide. After sitting aground for 15 or 20 minutes a guy came by in a 26' commercial bowpicker and left my boat sitting there. His jet sucked up every bit of water and spit it out behind; it looked like a scale model of the parting of the Red Sea until it filled in behind the boat as he cruised by without a problem. The 17' Svendson would run in less than an inch with the same appearance of using up all the water behind the boat until it filled back in.
I don't blame you for experimenting with what you have, but after experiencing properly set up boats designed for the purpose I would not mess with setting up an outboard jet whaler.
I have to admit that every once in a while when I see a cheap 25' inboard Temptation advertised I wonder what it would do with a 496 and a Hamilton Jet. I try not to ponder it too long...wasted brain power tends to have a cumulative effect on me.

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Author	Topic: 13-footer: Yamaha Jet Outboard
Riptide23WA	posted 01-02-2007 01:19 AM ET (US) While thumbing thru an old 1997 Yamaha brochure the other night, I got to thinking about the possiblity of plopping a small Yamaha jet outboard on the back of my project 13-foot classic Boston Whaler boat. [Yamaha] made a 35- and 28-HP. The weight looks a little much at 170 and 158 pounds, but I plan to mount the gas tank amidships, so that might counteract it a bit. I want to make this boat a shallow water fishing boat, and thought this might fit the bill. Anybody have experience with such a combo? Pat
anthonylisske	posted 01-02-2007 09:05 AM ET (US) One thing to consider is that there is approx. a 20% power loss with the jets. (i.e. - 100HP prop = 80hp jet) My Brother lives on the shore of a large salt water estuary and I was thinking what you where thinking, but in the end it was much more expensive, and much more hassle than a proped motor.
runpasthefence	posted 01-02-2007 09:37 AM ET (US) There was an outboard jet lower unit attachment on sale on Ebay a few months back that would fit my Yamaha for my 15' CC. I did some research to determine if it would be a smart buy. The amount of water needed to run a boat with a jet outboard is amazing. However, what kept me from buying that unit was the fact that although you can run in 3-4" of water, you still would need a significant amount of depth to get back on plane once you stop. I figured there aren't many situations (for me) when I would encounter that shallow of water then end up in deep enough water to re-plane.
The Judge	posted 01-02-2007 01:51 PM ET (US) Depends on what type of bottom you are running across. Rocky, then jets are great and maybe even necessary. Mud, you will suck it up in a heartbeat. The new jets are jet rated hp. That 35 is probably a 50hp prop engine so 35hp, jet. 28 is probably a 40, hence why they are expensive. Main problem with jets is they do not like to go slow. If you are the type to run 5000 rpms all day, jets are good. If you are like me and like to loaf along at 22mph, you will probably find jets a tad finicky. Try going slow cruise on a jetski.
Teak Oil	posted 01-02-2007 03:32 PM ET (US) Also this may not be a good option if you are going into shallow weedy areas. Spending all day pulling weeds out of the impeller over and over again is not relaxing
PeteB88	posted 01-02-2007 09:52 PM ET (US) Probably not the right thing to do - listen to the advice. Outboard jets were designed for Western rivers way back, rocky, some sand, little weed problems - to push boats through fast water, shallow and rapids. I can run my 13 in very little water w/ prop - into mud, weeds etc when fishing with top waters. Jet would be impossible and you lose way too much power. As far as I'm concerned jet pumps are indicated for places that would shred the blades off a propeller.
Riptide23WA	posted 01-03-2007 12:12 AM ET (US) Sheesh, it all sounds like sage advice. I am aiming to fish the sandy flats near where I live... hadn't thought about the sand/mud factor. And the low rpm performance is a good point too. This has been a question I've had for awhile. I should have asked a long time ago, and quit wasting brain power on it... Thanks to all. Pat
PeteB88	posted 01-03-2007 10:27 AM ET (US) We got your back Riptide, that's what this is all about. My fishin pal had to have a jet boat set up for river fishing and insisted that a 25 Merc w/ pump would be perfect. Ya right. He goes over 225 lbs and so do his friends. You probably guessed it - joke, not enough power and in current that = dangerous. Enjoy and Happy New year.
Riptide23WA	posted 01-03-2007 10:34 PM ET (US) Thanks Pete. I have often wondered about marrying an OMC jet from a Rage or other jet boat, to a flats boat hull. I think one would end up with a low profile stern/fishing platform, with no OB to tilt up, or jackplate up. Wouldn't need a poling platform over the engine either. I guess I know why it hasn't been done now... Pat
logjam	posted 01-09-2007 05:09 PM ET (US) I wouldn't totally give up on the idea of a flats jet boat but the idea of trying to make one out of a whaler is not the best idea. The hull design and shape are not the problem. It will work I have experimented some with it on an 11 and a 17; both worked but were underpowered carrying a load. The problem is the weight. In order to make a jet boat work well you need to keep it light or throw a lot of horsepower and a big jet at it. Setting up a whaler as a flats boat is kind of defeating the purpose of having a flats boat. Compared to a light boat of the same size it would be hard to pole, take two or three times as much water off the step and be hard to get unstuck when you make a mistake. I don't know what you are up against on your flats but I have used both outboard jets and inboard jets on The Copper, Stikine, and Yukon Deltas as well as the connected river systems. All three systems have lots of sand, mud and glacial silt as well as rock and gravel higher in the river systems. It seemed that the only places that caused any real problems were clogging the grates with smll rocks or large gravel when trying to start in shallow water and trash running in some weed beds. By far the most fun I had was with a 17'Welded aluminum skiff made by Svendson Marine in Wrangell. The outboard jet was recessed into a ramped tunnel and the shallow water performance was truly amazing. It seemed that if you saw water you could go as long as you didn't stop. Getting going in shallow water was usually not a problem if the boat would float unless trying to start in gravel or small rocks. On the Copper River Delta 1/2 of the commercial fleet uses jet drives in 26'-32' inboard bowpickers. We are talking sand, mud, and silt in shallow sloughs as well as surf where the big gulf of alaska swell hits the shallow waters of the Delta. In this environment the jet rigs are far superior to anything else. In addition the maintenance is much less than outdrives which tend to get destroyed in the harsh working conditions. The jets will run efficiently in shallow water but the efficiency starts dropping in deep water and cavitation can be a problem in rough water. Everyone tries to run in shallow water to pick up speed and save fuel. Most try to deliver fish to tenders in an effort to keep boats lighter but still these boats are hauling far more ice, fish, and gear than the average sportfishing vessel. If the concept of a jet drive didn't work the commercial fleet would not be using them. I think that jet units often get a bad rap from guys that are trying to use an improperly sized, misadjusted, or worn out impeller; Also from guys asking too much from an underpowered engine or too small a jet. If you did decide to try a jet on your 13 you will need to put a bracket on the transom to get the jet to the right level. The 50hp powerhead would probably be just about right but don't expect it to run with a light jet boat with a ramped tunnel. Greg
contender	posted 01-10-2007 10:20 PM ET (US) If jets are so good why dont you see more of them, get the prop...good luck
logjam	posted 01-10-2007 11:17 PM ET (US) I have to agree. If I were powering a 13' whaler I would use a prop. If I wanted fuel efficiency at cruise in water over a foot or two I would use a prop. If I wanted to run in the same depth of water that people use boogie boards to keep from crossing dangerous surf or go through surf without leaving a lower unit or outdrive behind I would use a jet and a boat designed for the purpose. My pro jet comments are not to encourage riptide to use a jet on a whaler. I would in fact discourage that. My pro jet comments are to encourage him to keep thinking outside of the Boston Whaler Box if he truly needs shallow water or surf performance and not to rule out a jet because of all the negative comments. I would try one in a similar area of use before buying one. I also encourage Riptide to keep thinking about all of his ideas. None of it is wasted brain power and someone has to be the first. It's only time and money!
Riptide23WA	posted 01-11-2007 11:18 PM ET (US) logjam, thanks for the insight. I have always been curious about jet performance, as my only experience has been aboard PWC's. I was thinking about the shallow water performance mainly, not top speed, or surfing, or anything else. You bring up a good point in that the 13 hull, with no tunnel, isn't really designed for a jet, although somebody posted some pix of a jet prototype from a long time ago... Still, were I to come across a jet OB cheap, I'd still wanna try it out. Ain't no lesson learned so well as the one you learned the hard way! '-) Anyway, the 13 may not make the best flats boat, but since I have two of them, I thought I'd set one up as a pocket fishing platform. Thanks again. Pat
logjam	posted 01-12-2007 08:01 AM ET (US) Pat, I think I gave the false impression that the jet actually rides in a tunnel like the prototype whaler that you mentioned. The ramp just allows water to flow up to the foot of the jet which is riding several inches higher than the bottom of the transom to keep it from hanging up on the sea floor. People ran jets for a long time before they started building ramps into the bottom of hulls to protect outboard jets. Without the ramp the jet foot has to hang down at least to the bottom of the transom where it is more prone to dragging or sucking up debris. Again I hate to see you put together a package that won't perform the way that it should. I'll always remember hanging up the foot of an outboard jet powered 11' in a channel with a sand bottom on a falling tide. After sitting aground for 15 or 20 minutes a guy came by in a 26' commercial bowpicker and left my boat sitting there. His jet sucked up every bit of water and spit it out behind; it looked like a scale model of the parting of the Red Sea until it filled in behind the boat as he cruised by without a problem. The 17' Svendson would run in less than an inch with the same appearance of using up all the water behind the boat until it filled back in. I don't blame you for experimenting with what you have, but after experiencing properly set up boats designed for the purpose I would not mess with setting up an outboard jet whaler. I have to admit that every once in a while when I see a cheap 25' inboard Temptation advertised I wonder what it would do with a 496 and a Hamilton Jet. I try not to ponder it too long...wasted brain power tends to have a cumulative effect on me.