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Author Topic:   jet drives

bugga posted 10-28-2003 02:00 PM ET (US)
I have an ~1980 11ft whaler with a 18hp merc. I'm wondering has anyone used a jet drive on a whaler of similar size and if so, how has it performed? Also, are there jet drive conversion kits for regular prop driven outbaords or do you need to buy a new motor?
If this is a truly dumb idea, please let me know. I would like to use the boat to run some shallow rocky water in michigan for steelheading. Thanks.
bugga

13DAUNTLESS posted 10-28-2003 05:37 PM ET (US)
Mercury makes a 25 hp jet outboard that puts out 20 hp at the drive. If it were my boat I would stick with a regular outboard with a prop protector for the times you are fishing in shallow rocky water. Good luck.
Tom2697 posted 10-29-2003 09:43 AM ET (US)
While I hate saying this, here is one area where Boston Whalers, or any fiberglass boat for that matter, do not work well. Rocks and fiberglass are NOT a good combination. If the water is shallow enough that you need a jet drive, chances are that you will cheese grate your bottom in no time. Consider a plate-hulled welded aluminum boat for this application.
Bigshot posted 10-29-2003 11:19 AM ET (US)
i have thought baout Jetdrive outboards for years but I think I would be VERY disappointed in midrange performance.
alkar posted 10-29-2003 11:00 PM ET (US)
Bugga, you can get conversions for most outboards through Outboard Jet Corp in San Leandro, California.
The outboard jets are wonderful for many applications, but there are many downsides as well:
1) Jets are loud
2) They suck fuel
3) There's a substantial loss of power to the jet - about 30-35% loss - more if the impeller or housing has become severely worn.
4) Poor reverse performance (with some exceptions)
5) Poor/slow steering response at lower speeds
6) Loss of "rudder" function of lower unit if vessel is
"coasting" or drifting.
7) It can be very difficult to clear a fouled impeller (like when the jet has sucked up 30 feet of your spider wire and stalled :)
8) They have no true neutral (If motor is running, pump is moving water and generating thrust).
In spite of all of the above, they're the best choice in some environments.
I agree with the other guys who posted.
I think I'd keep the prop on your whaler and buy a WELDED aluminum boat with a jet for the rocky, shallow water. (Welded aluminum jets are very popular in the northwest. They are vastly superior to their flimsey rivited aluminum counterparts.)
Sal DiMercurio posted 10-29-2003 11:29 PM ET (US)
First of all, i'v run many jet drives & theres a hell of alot more hp loss then 30/35 percent, more like 50 percent & 50 percent of an 18 hp is 9 hp.
Now, in order to get "ANYTHING" that resembles performance, that engine & any other engine "MUST" be run wide open with a jet drive,.....do you have any idea how long an engine will last if you ran it wide open/
You will burn 3 times as much fuel as the guy running right along side of you in the same rig with a prop.
The wear & tear on the engine will "NOT" justify being able to run over rocks believe me.
Sal
alkar posted 11-01-2003 11:34 AM ET (US)
Sal, I respectfully disagree with your 50% figure, and so do all the major motor manufacturers who deliver jet drives and "jet ready" motors.
Mercury, Yamaha, and Honda have all been delivering 90/65 motors, for example, for many years (90HP powerhead w/ 65 claimed net horsepower at the jet).
My last Outboard jet was a Yamaha F115/80 on a heavy 20 foot welded aluminum sled. It performed well under very heavy loads in mid RPM ranges - even heading up river in whitewater where there is less "traction". That motor seldom saw WOT.
We had the same boat in an 18 footer with a Honda 90/65 that we used as a gear-barge to carry gear up and down the Rogue River for camping & fishing trips. We could (and did)load that boat with gear above the gunwales - and it still performed got up through the whitewater comfortably. That boat, now four years old, was sold to a friend of mine after it left commercial service. It still sees year-round use, and it's still running like a watch.
Sal DiMercurio posted 11-01-2003 11:13 PM ET (US)
He's talking about an 18 hp.
Thats not the type of engine to put a jet on.
All the ones i'v been in & ran were real dogs through & through.
The biggest engine was a 115 hp & if it put out 60 hp i'd really be surprised, it was a dog & had to be run wide open all the time just to stay on plane on a 18 ft fiberglass semi V bottom.
Sal
AQUANUT posted 11-02-2003 11:08 AM ET (US)
impeller vs propeller....
I agree with all posted ..I convert 2{S} and 4{S} on a daily basis.....mercury and yamahas..@ a dealership...for both, bw and an jetboat {sled} line....although I am constantly learning..things change often in life....a 18 hp jet would double as a second anchor in my opinion....two stroke 90/115s with tiller drive handles and the right impellers are a handfull on the right hulls..lotsa fun....however...with the 30 percent on average loss of power on new...i say again..NEWER....outboards...benefits are few on an open water fiberglas hulled boat.
there are many different types of boats formany different types of boating environments....go propeller on a whaler
alkar posted 11-02-2003 05:15 PM ET (US)
Sal, Aquanut made a good point. The 30% figure assumes a newer pump. Many folks use the outboard jets on rivers containing lots of small rock and sand in the bottom. When the pumps ground or beach, they often suck some little rocks through the grate in the shoe That will beat and grinds an impeller to death.
I've seen some TRASHED impellers come out of units less than two years old Those units probably were losing more than 50% of their power because of the added turbulence in the housing.
HLP posted 08-07-2005 09:01 PM ET (US)
IT SOUNDS LIKE THE LOWER POWERED JETDRIVES MAY NOT THE CATS MEOW BUT I RECENTLY WENT FISHING ON THE WHITE RIVER IN THE ARKANSAS OZARKS WITH A GUIDE THAT HAD FISHED THAT RIVER FOR 39 YEARS. HE HAD A LONG FIBER GLASS BOAT AND A LARGE HIGH HORSE POWERED MERCURY OUTBOARD THAT WAS A JET DRIVE. HE WENT UP THAT RIVER AND ACROSS AREAS THAT COULDN'T HAVE BEEN MORE THAN A FEW INCHES. HE WENT PAST WITH EASE ALL OF THE PROP POWERED BOATS. MOST OF THE GUIDES ON THE RIVER HAD FIBERGLASS BOATS. I ASKED MY GUIDE. WHY A FIBER GLASS BOAT. HE SAID IF HE PUNCHED A HOLE IN THE BOTTOM OF HIS BOAT IT WAS VERY DIFFICULT TO FIX. BUT IF HE DID HIS FIBERGLASS BOAT IT WAS EASY AND QUICK TO FIX. HE SAID MY BOAT IS MY LIFE'S BUSINESS. IF I GET A HOLE IN THE BOTTOM OF MY BOAT I CAN HAVE IT FIXED THE SAME EVENING BY MYSELF AND BE BACK IN BUSINESS THE NEXT DAY. HE ALSO SAID THE FIBER GLASS SLIDES OVER THE ROCKS MUCH MUCH EASIER THAN THE ALUMINUM BOATS THAT SEEM TO STICK ON THE ROCKS. I THEN WENT TO GASTONS TO CHECK OUT THEIR BOATS. THEY WERE ALL I MEAN ALL FIBER GLASS. THE GUIDES ALL TOLD ME THE SAME THING. FIBERGLASS. SLIDES EASY AND EASY TO FIX. HOWEVER THE GUIDES AT GASTON STILL HAD PROPS ON THEIR BOATS. SOME GUIDES SAID THEY SURE WISH THEY HAD JETDRIVE MOTORS BUT THE COMPANY WOULD HAVE TO UP THE MONEY FOR THEM.
SO I DON'T KNOW IF YOU WANT TO SCRATCH THE HELL OUT OF THE BOTTOM OF YOUR EXPENSIVE BOSTON WHALER ON THE BOTTOM OF THE RIVER. BOSTON WHALERS SEEM GREAT BECAUSE THEY CANNOT SINK HOWEVER IF YOU ARE SCRAPING BOTTOM MOST OF THE TIME THEN I SUPPOSE YOU ARE NOT WORRYING ABOUT SINKING.
PS. THE REASON I AM ANSWEREING THIS IS THAT I AM CONSIDERING A JET DRIVE FOR A 11 FOOT BOSTON WHALER TENDER TO COME UP TO SHALLOW AREAS ON THE BEACH.

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Author	Topic: jet drives
bugga	posted 10-28-2003 02:00 PM ET (US) I have an ~1980 11ft whaler with a 18hp merc. I'm wondering has anyone used a jet drive on a whaler of similar size and if so, how has it performed? Also, are there jet drive conversion kits for regular prop driven outbaords or do you need to buy a new motor? If this is a truly dumb idea, please let me know. I would like to use the boat to run some shallow rocky water in michigan for steelheading. Thanks. bugga
13DAUNTLESS	posted 10-28-2003 05:37 PM ET (US) Mercury makes a 25 hp jet outboard that puts out 20 hp at the drive. If it were my boat I would stick with a regular outboard with a prop protector for the times you are fishing in shallow rocky water. Good luck.
Tom2697	posted 10-29-2003 09:43 AM ET (US) While I hate saying this, here is one area where Boston Whalers, or any fiberglass boat for that matter, do not work well. Rocks and fiberglass are NOT a good combination. If the water is shallow enough that you need a jet drive, chances are that you will cheese grate your bottom in no time. Consider a plate-hulled welded aluminum boat for this application.
Bigshot	posted 10-29-2003 11:19 AM ET (US) i have thought baout Jetdrive outboards for years but I think I would be VERY disappointed in midrange performance.
alkar	posted 10-29-2003 11:00 PM ET (US) Bugga, you can get conversions for most outboards through Outboard Jet Corp in San Leandro, California. The outboard jets are wonderful for many applications, but there are many downsides as well: 1) Jets are loud 2) They suck fuel 3) There's a substantial loss of power to the jet - about 30-35% loss - more if the impeller or housing has become severely worn. 4) Poor reverse performance (with some exceptions) 5) Poor/slow steering response at lower speeds 6) Loss of "rudder" function of lower unit if vessel is "coasting" or drifting. 7) It can be very difficult to clear a fouled impeller (like when the jet has sucked up 30 feet of your spider wire and stalled :) 8) They have no true neutral (If motor is running, pump is moving water and generating thrust). In spite of all of the above, they're the best choice in some environments. I agree with the other guys who posted. I think I'd keep the prop on your whaler and buy a WELDED aluminum boat with a jet for the rocky, shallow water. (Welded aluminum jets are very popular in the northwest. They are vastly superior to their flimsey rivited aluminum counterparts.)
Sal DiMercurio	posted 10-29-2003 11:29 PM ET (US) First of all, i'v run many jet drives & theres a hell of alot more hp loss then 30/35 percent, more like 50 percent & 50 percent of an 18 hp is 9 hp. Now, in order to get "ANYTHING" that resembles performance, that engine & any other engine "MUST" be run wide open with a jet drive,.....do you have any idea how long an engine will last if you ran it wide open/ You will burn 3 times as much fuel as the guy running right along side of you in the same rig with a prop. The wear & tear on the engine will "NOT" justify being able to run over rocks believe me. Sal
alkar	posted 11-01-2003 11:34 AM ET (US) Sal, I respectfully disagree with your 50% figure, and so do all the major motor manufacturers who deliver jet drives and "jet ready" motors. Mercury, Yamaha, and Honda have all been delivering 90/65 motors, for example, for many years (90HP powerhead w/ 65 claimed net horsepower at the jet). My last Outboard jet was a Yamaha F115/80 on a heavy 20 foot welded aluminum sled. It performed well under very heavy loads in mid RPM ranges - even heading up river in whitewater where there is less "traction". That motor seldom saw WOT. We had the same boat in an 18 footer with a Honda 90/65 that we used as a gear-barge to carry gear up and down the Rogue River for camping & fishing trips. We could (and did)load that boat with gear above the gunwales - and it still performed got up through the whitewater comfortably. That boat, now four years old, was sold to a friend of mine after it left commercial service. It still sees year-round use, and it's still running like a watch.
Sal DiMercurio	posted 11-01-2003 11:13 PM ET (US) He's talking about an 18 hp. Thats not the type of engine to put a jet on. All the ones i'v been in & ran were real dogs through & through. The biggest engine was a 115 hp & if it put out 60 hp i'd really be surprised, it was a dog & had to be run wide open all the time just to stay on plane on a 18 ft fiberglass semi V bottom. Sal
AQUANUT	posted 11-02-2003 11:08 AM ET (US) impeller vs propeller.... I agree with all posted ..I convert 2{S} and 4{S} on a daily basis.....mercury and yamahas..@ a dealership...for both, bw and an jetboat {sled} line....although I am constantly learning..things change often in life....a 18 hp jet would double as a second anchor in my opinion....two stroke 90/115s with tiller drive handles and the right impellers are a handfull on the right hulls..lotsa fun....however...with the 30 percent on average loss of power on new...i say again..NEWER....outboards...benefits are few on an open water fiberglas hulled boat. there are many different types of boats formany different types of boating environments....go propeller on a whaler
alkar	posted 11-02-2003 05:15 PM ET (US) Sal, Aquanut made a good point. The 30% figure assumes a newer pump. Many folks use the outboard jets on rivers containing lots of small rock and sand in the bottom. When the pumps ground or beach, they often suck some little rocks through the grate in the shoe That will beat and grinds an impeller to death. I've seen some TRASHED impellers come out of units less than two years old Those units probably were losing more than 50% of their power because of the added turbulence in the housing.
HLP	posted 08-07-2005 09:01 PM ET (US) IT SOUNDS LIKE THE LOWER POWERED JETDRIVES MAY NOT THE CATS MEOW BUT I RECENTLY WENT FISHING ON THE WHITE RIVER IN THE ARKANSAS OZARKS WITH A GUIDE THAT HAD FISHED THAT RIVER FOR 39 YEARS. HE HAD A LONG FIBER GLASS BOAT AND A LARGE HIGH HORSE POWERED MERCURY OUTBOARD THAT WAS A JET DRIVE. HE WENT UP THAT RIVER AND ACROSS AREAS THAT COULDN'T HAVE BEEN MORE THAN A FEW INCHES. HE WENT PAST WITH EASE ALL OF THE PROP POWERED BOATS. MOST OF THE GUIDES ON THE RIVER HAD FIBERGLASS BOATS. I ASKED MY GUIDE. WHY A FIBER GLASS BOAT. HE SAID IF HE PUNCHED A HOLE IN THE BOTTOM OF HIS BOAT IT WAS VERY DIFFICULT TO FIX. BUT IF HE DID HIS FIBERGLASS BOAT IT WAS EASY AND QUICK TO FIX. HE SAID MY BOAT IS MY LIFE'S BUSINESS. IF I GET A HOLE IN THE BOTTOM OF MY BOAT I CAN HAVE IT FIXED THE SAME EVENING BY MYSELF AND BE BACK IN BUSINESS THE NEXT DAY. HE ALSO SAID THE FIBER GLASS SLIDES OVER THE ROCKS MUCH MUCH EASIER THAN THE ALUMINUM BOATS THAT SEEM TO STICK ON THE ROCKS. I THEN WENT TO GASTONS TO CHECK OUT THEIR BOATS. THEY WERE ALL I MEAN ALL FIBER GLASS. THE GUIDES ALL TOLD ME THE SAME THING. FIBERGLASS. SLIDES EASY AND EASY TO FIX. HOWEVER THE GUIDES AT GASTON STILL HAD PROPS ON THEIR BOATS. SOME GUIDES SAID THEY SURE WISH THEY HAD JETDRIVE MOTORS BUT THE COMPANY WOULD HAVE TO UP THE MONEY FOR THEM. SO I DON'T KNOW IF YOU WANT TO SCRATCH THE HELL OUT OF THE BOTTOM OF YOUR EXPENSIVE BOSTON WHALER ON THE BOTTOM OF THE RIVER. BOSTON WHALERS SEEM GREAT BECAUSE THEY CANNOT SINK HOWEVER IF YOU ARE SCRAPING BOTTOM MOST OF THE TIME THEN I SUPPOSE YOU ARE NOT WORRYING ABOUT SINKING. PS. THE REASON I AM ANSWEREING THIS IS THAT I AM CONSIDERING A JET DRIVE FOR A 11 FOOT BOSTON WHALER TENDER TO COME UP TO SHALLOW AREAS ON THE BEACH.