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Author Topic:   Jet Drive Outboard for 16-Dauntless

chuckster posted 09-14-2002 03:15 PM ET (US)
I'm new to this forum so bear with me. I live in the Great Lakes area and boat and fish the coastal waters. As you might not know, water levels here have been dropping through the years and I'm trashing prop after prop on floating debris. Is it possible to install a new Merc 80 4-stroke Outboard jet on a 16 Dauntlass? Shaft length is same as factory prop units. Has anyone experience with these Mercs? I know Yamaha makes a full line of them also. Since Mercs are all BW will equip their new whalers with, maybe they'd sell me a new 16 with an outboard jet of their own on it? Or than maybe Im just crazy?
dscew posted 09-14-2002 04:08 PM ET (US)
To run a jet pump on a boat as heavy as the 16 Dauntless, you'd need twice the power you're thinking of. Jets require much more power since there's no direct interface with the water like there is with a prop. I don't think it work in that application. Older BW jets were very underpowered.
chuckster posted 09-14-2002 04:34 PM ET (US)
Thanks dscew, your prob right as my knowledge of outboard jets is small. Just thought that there big 80 jet might do it since its rated 115HP at the impeller. But I believe your right, because that transfers to I believe a true 80 hp. And THAT aint gonna cut it. Wish they'd come out with bigger outboard jets. (guess there working on it from what I read). Engine weights are more or less the same as standard 4-strokes. Guess ILL have-ta keep the prop manufacturers in business for awhile.
Jerry Townsend posted 09-14-2002 05:08 PM ET (US)
Chuckster - a jet is about 30 % less efficient than a prop - so that spells bigger engine, et.al. Also, since you like to fish - a jet doesn't troll - period - so if you want to troll, you would have to have a small kicker.
A thought - consider a shroud around your prop - some use them in keeping weeds out of a prop - but they would also keep debris away from the prop as well. I haven't used one, but they appear to be pretty well built and could work. ---- Jerry/Idaho
lhg posted 09-14-2002 06:10 PM ET (US)
Are you trashing an aluminum or SS prop? If aluminum, switch to SS and you should have a lot less problems. If you're already damaging SS props, you may have to start reading the charts better! I have boated the Great lakes for over 20 years, and never so much as put a ding in an SS prop.
I concur to stay away from a jet outboard for the Great Lakes.
chuckster posted 09-14-2002 08:21 PM ET (US)
Where can I pick up a shroud like your talking about? That might help. Most of the junk Im hitting aint on charts, (floating logs, tops of sunkin Ice fishing shanties that were not pulled ashore...so-forth.) But I think your right...a ss prop would go along way. Just hate payin the big bucks for one. Love my whaler...would never give THAT up. Would a shroud like that effect performance? anyone had any experience with one? Thanks you guys for all your Knowledge.
dscew posted 09-15-2002 11:43 AM ET (US)
I would advise against a SS prop. If you hit something solid with SS, you risk breaking the prop shaft and gears as well. Stainless doesn't give like aluminum does. If you break aluminum, you replace the prop. If you break SS, you may have a higher repair bill. And just the prop replacement cost is 3 times that of aluminum. Check out composite props. They're cheap, you can carry a spare, and they're pretty reliable.
Jerry Townsend posted 09-15-2002 03:00 PM ET (US)
Chuckster - the shrouds are available via West Marine as well as at least another (can't recall the name right now - Cabella's or maybe Boater's World).
The shroud should not affect the economy too much - one way or the other. There will be some drag, but counter-acting that loss, the shroud should improve the effeciency of the prop by reducing/eliminating the tip wash losses.
Dscew already mentioned the detriments of your using a ss prop. Another problem is that hitting something solid with a solid prop can cause the prop to spin (shearing the rubber interface between the shaft spline and the prop) - which is also bad news and basically says - fix it or buy a new one. ------- Jerry/Idaho
jimh posted 09-15-2002 03:39 PM ET (US)
The current lake levels are only a few inches below their long-term averages.
This may seem obvious but I cannot help but observe that "floating debris" is afloat, and it does not seem obvious to me how the water level being a few inches down makes contact with floating debris more likely. It is...floating!
If anything, periods of high water would be more likely to cause an increase in floating debris, since high water would tend to wash material from banks, etc. Floating debris always seem more common in spring when high water levels from winter snow melts and run offs carry much material into the water.
jimh posted 09-15-2002 03:45 PM ET (US)
[Changed TOPIC; was "Dont [sic] think Im [sic] crazy...but..."--jimh.]
lhg posted 09-16-2002 02:08 PM ET (US)
I have to disagree with the comments here that say an SS prop is more likely to damage an ENGINE than an aluminum. Millions are in use on outboards of all sizes and you don't ever hear of lower unit damage from the prop. Admittedly, all of my experience is with Mercury props, but the greatly enhanced durability and ability of the SS to shrug off damage that would otherwise kill an aluminum prop is proven. A few years ago I hit a partially submerged floating telephone pole up in BC, and the SS prop only had a small ding in it. This was easily straightened out with a pliers at the next dock, and my trip was not ruined. An aluminum prop would have been destroyed by this encounter, believe me.
What is being forgotten is that it is the hub design that really matters in protecting the engine drive train. Some brands are better than others. The older style rubber hubs, and now the even better plastic drop-in hub, which is completely interchangeable and replaceable by the consumer, will shear to protect the engine if the encounter is that bad. You can even carry a spare plastic hub kit with you.
I'm sticking with my recommendation that chuckster get a modern hub designed SS prop, either by Mercury or Michigan wheel, regardless of his engine brand, and his problems will be over.

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Author	Topic: Jet Drive Outboard for 16-Dauntless
chuckster	posted 09-14-2002 03:15 PM ET (US) I'm new to this forum so bear with me. I live in the Great Lakes area and boat and fish the coastal waters. As you might not know, water levels here have been dropping through the years and I'm trashing prop after prop on floating debris. Is it possible to install a new Merc 80 4-stroke Outboard jet on a 16 Dauntlass? Shaft length is same as factory prop units. Has anyone experience with these Mercs? I know Yamaha makes a full line of them also. Since Mercs are all BW will equip their new whalers with, maybe they'd sell me a new 16 with an outboard jet of their own on it? Or than maybe Im just crazy?
dscew	posted 09-14-2002 04:08 PM ET (US) To run a jet pump on a boat as heavy as the 16 Dauntless, you'd need twice the power you're thinking of. Jets require much more power since there's no direct interface with the water like there is with a prop. I don't think it work in that application. Older BW jets were very underpowered.
chuckster	posted 09-14-2002 04:34 PM ET (US) Thanks dscew, your prob right as my knowledge of outboard jets is small. Just thought that there big 80 jet might do it since its rated 115HP at the impeller. But I believe your right, because that transfers to I believe a true 80 hp. And THAT aint gonna cut it. Wish they'd come out with bigger outboard jets. (guess there working on it from what I read). Engine weights are more or less the same as standard 4-strokes. Guess ILL have-ta keep the prop manufacturers in business for awhile.
Jerry Townsend	posted 09-14-2002 05:08 PM ET (US) Chuckster - a jet is about 30 % less efficient than a prop - so that spells bigger engine, et.al. Also, since you like to fish - a jet doesn't troll - period - so if you want to troll, you would have to have a small kicker. A thought - consider a shroud around your prop - some use them in keeping weeds out of a prop - but they would also keep debris away from the prop as well. I haven't used one, but they appear to be pretty well built and could work. ---- Jerry/Idaho
lhg	posted 09-14-2002 06:10 PM ET (US) Are you trashing an aluminum or SS prop? If aluminum, switch to SS and you should have a lot less problems. If you're already damaging SS props, you may have to start reading the charts better! I have boated the Great lakes for over 20 years, and never so much as put a ding in an SS prop. I concur to stay away from a jet outboard for the Great Lakes.
chuckster	posted 09-14-2002 08:21 PM ET (US) Where can I pick up a shroud like your talking about? That might help. Most of the junk Im hitting aint on charts, (floating logs, tops of sunkin Ice fishing shanties that were not pulled ashore...so-forth.) But I think your right...a ss prop would go along way. Just hate payin the big bucks for one. Love my whaler...would never give THAT up. Would a shroud like that effect performance? anyone had any experience with one? Thanks you guys for all your Knowledge.
dscew	posted 09-15-2002 11:43 AM ET (US) I would advise against a SS prop. If you hit something solid with SS, you risk breaking the prop shaft and gears as well. Stainless doesn't give like aluminum does. If you break aluminum, you replace the prop. If you break SS, you may have a higher repair bill. And just the prop replacement cost is 3 times that of aluminum. Check out composite props. They're cheap, you can carry a spare, and they're pretty reliable.
Jerry Townsend	posted 09-15-2002 03:00 PM ET (US) Chuckster - the shrouds are available via West Marine as well as at least another (can't recall the name right now - Cabella's or maybe Boater's World). The shroud should not affect the economy too much - one way or the other. There will be some drag, but counter-acting that loss, the shroud should improve the effeciency of the prop by reducing/eliminating the tip wash losses. Dscew already mentioned the detriments of your using a ss prop. Another problem is that hitting something solid with a solid prop can cause the prop to spin (shearing the rubber interface between the shaft spline and the prop) - which is also bad news and basically says - fix it or buy a new one. ------- Jerry/Idaho
jimh	posted 09-15-2002 03:39 PM ET (US) The current lake levels are only a few inches below their long-term averages. This may seem obvious but I cannot help but observe that "floating debris" is afloat, and it does not seem obvious to me how the water level being a few inches down makes contact with floating debris more likely. It is...floating! If anything, periods of high water would be more likely to cause an increase in floating debris, since high water would tend to wash material from banks, etc. Floating debris always seem more common in spring when high water levels from winter snow melts and run offs carry much material into the water.
jimh	posted 09-15-2002 03:45 PM ET (US) [Changed TOPIC; was "Dont [sic] think Im [sic] crazy...but..."--jimh.]
lhg	posted 09-16-2002 02:08 PM ET (US) I have to disagree with the comments here that say an SS prop is more likely to damage an ENGINE than an aluminum. Millions are in use on outboards of all sizes and you don't ever hear of lower unit damage from the prop. Admittedly, all of my experience is with Mercury props, but the greatly enhanced durability and ability of the SS to shrug off damage that would otherwise kill an aluminum prop is proven. A few years ago I hit a partially submerged floating telephone pole up in BC, and the SS prop only had a small ding in it. This was easily straightened out with a pliers at the next dock, and my trip was not ruined. An aluminum prop would have been destroyed by this encounter, believe me. What is being forgotten is that it is the hub design that really matters in protecting the engine drive train. Some brands are better than others. The older style rubber hubs, and now the even better plastic drop-in hub, which is completely interchangeable and replaceable by the consumer, will shear to protect the engine if the encounter is that bad. You can even carry a spare plastic hub kit with you. I'm sticking with my recommendation that chuckster get a modern hub designed SS prop, either by Mercury or Michigan wheel, regardless of his engine brand, and his problems will be over.