Great info, Stanley...thanks. I had *absolutely* no clue that I could
potentially increase the speed by using a higher pitch prop. My
impression was always that your prop should allow your engine to get to
it's max rpm in order to get max speed (which mine does)...guess I was
wrong. But still, I'm not sure I want to spend ~$200 for a new prop to
gain a few mph.

Stanley Barthfarkle wrote:
:Your theoretical top speed with your current configuration is 32.5 mph at
:5100 rpm.
:Your theoretical top speed with a 14 x 19 prop is 34.1 mph at 4800 rpm.
:Your theoretical top speed with a 14 x 21 prop is 35.8 mph at 4550 rpm.
:
:Prop info: (note- 15% is the average amount of prop "slip")
:http://powerboat.about.com/cs/propel...llingfacts.htm
:http://www.a1discountprop.com/propinfo.htm
:http://www.rbbi.com/folders/prop/propcalc.htm
:http://www.csgnetwork.com/marinepropcalc.html
:http://www.go-fast.com/Prop_Slip_Calculator.htm
:http://www.fishweb.com/recreation/bo...ps/props1.html
:
:
:
:"Bob" wrote in message
...
: It's a model 270D...2.15:1 gear ratio. When the boat was brand new
: (1972) and using the same pitch prop, the top-end was always 31-32 mph,
: so I feel good that I can get there with a rebuilt engine. Will a
: higher pitched prop, say a 14x19, drop the WOT rpms? If so, how does
: that equate to a higher WOT speed? Seems like it would do the opposite,
: but like I say I don't know much about props.
:
:
: Stanley Barthfarkle wrote:
: :Bob, what model is your outdrive? Do you know the gear ratio? Seems to me
: :that you should be able to swing a more aggressively pitched prop (more
: :top-end speed) with that engine, but it would help to know your outdrive
: :specs.
: :
: :
: :"Bob" wrote in message
: ...
: : I am using a standard (aluminum?) 14x17 prop, which seems to match the
: : boat well because my WOT is about 5200 rpm, but than again I don't know
: : much about props. I do have a Sting Ray hydrofoil but I prefer not to
: : use it unless I am going to be carrying a large load...it surely helps
: : me get up on plane faster, but it also reduces my top end by a few mph
: : as well as making the steering feel "tight" and not as responsive as
: : without it. One thing that is different on my boat than many of the
: : newer boats, is that the bow is closed so I can't put passengers up
: : there, which probably does not affect the top speed, but sure does
: : impact the ability to plane quickly when the boat has more than a few
: : adults in it.
: :
: :
: : Stanley Barthfarkle wrote:
: : : What prop are you using? Do you have a Sting Ray Hydrofoil? If not,
:get
: : ne. Boat planes better, and it allows use of a higher pitched prop
14 X
: :21
: : :SS cupped in my case). Less cavitation, and no "rooster tail"- energy
: :that
: : :would have been wasted with a rooster tail is sent rearward,
:increasing
: : ropulsion.
: : :
: : :
: : :"Bob" wrote in message
: : ...
: : : Dang, how do you get so much speed out of your little Volvo engine?
:I
: : : have a newly rebuilt AQ130C ( 4 cyl. 130 hp) and it only takes my
:boat
: : : up to 31 mph at WOT, about 5000 rpm with two adults in it. My boat
:is
: : : a 17' fiberglass v-hull and weighs about 2000 lbs I would guess, and
: : : has a Volvo 270 outdrive on it.
: : :
: : : BTW, it consumes just 3-4 gph at cruise speed (4200 rpm, 27 mph).
: : :
: : : Bob
: : :
: : : Stanley Barthfarkle wrote:
: : : :1985 Bayliner 1952 cuddy
: : : :18.5' fiberglass 'modified V' hull
: : : :19.5' Length over all
: : : :2200 lbs dry weight
: : : :1985 Volvo Penta AQ125B 4 cyl 105 hp 4 stroke
: : : :1 barrel Solex carb 35 mm
: : : :Volvo Penta 270 Stern drive
: : : :14 X 19 modified SS 3-blade prop (14 X 21 effective)
: : : :StingRay Hydrofoil
: : : :35 mph WOT @ 4800 RPM
: : : :32 mph cruise @ 4400 RPM
: : : :
: : : :Premium unleaded fuel (92 octane)
: : : :4 adults & 1 dog, ski equipment, coolers, etc-
: : : :6-7 gph WOT
: : : :5 gph cruise
: : : :
: : : :
: : : :
: : : :"Matt Lang" wrote in message
: : : . com...
: : : : Guys,
: : : :
: : : : I am thinking about getting a harbercraft jetboat ... these
:things
: :are
: : : : made from aluminum and have the 175 HP Mercury sportjet..
: : : :
: : : : So far so good ... Now what raises the fuel warning flag are the
: : : : terms:
: : : :
: : : : - jet
: : : : - 2 stroke
: : : : - carburator (two of them
: : : :
: : : : The boat will burn about 5 gallons per hour at 30 mph... now I
:was
: : : : wondering how this compares to a similar sized fiberglass hboat
:with
: : : : 115-150 HP 4 Stroke outboard..
: : : :
: : : : What is the fuel you burn at cruise speed and WOT, whats your
:boat
: : : : size/weight and what motor are you running ..
: : : :
: : : : I am interested in how the relatively light alu jetboat compares
:to
: :a
: : : : more conventional boat with 4 stroke motor..
: : : :
: : : : Any info is appreciated
: : : :
: : : :
: : : : Matt
: : : :
: : : :
: : :
: : :
: : :
: : :
: :
: :
: :
: :
:
:
:
:

I'm sitting here looking at this info in amazement... I have dual 283
engines on the ChrisCraft which I haven't even had running to get any idea
of what RPM's should be on it... Wondering what difference there could be
with props and such...

Will get the ratio, gearbox info when I get back to the shop tonight...
Perhaps someone could help me figure it out.

http://www.wildhorse-webdesign.com/boat

"Bob" wrote in message
...

Great info, Stanley...thanks. I had *absolutely* no clue that I could
potentially increase the speed by using a higher pitch prop. My
impression was always that your prop should allow your engine to get to
it's max rpm in order to get max speed (which mine does)...guess I was
wrong. But still, I'm not sure I want to spend ~$200 for a new prop to
gain a few mph.

Stanley Barthfarkle wrote:
:Your theoretical top speed with your current configuration is 32.5 mph at
:5100 rpm.
:Your theoretical top speed with a 14 x 19 prop is 34.1 mph at 4800 rpm.
:Your theoretical top speed with a 14 x 21 prop is 35.8 mph at 4550 rpm.
:
:Prop info: (note- 15% is the average amount of prop "slip")
:http://powerboat.about.com/cs/propel...llingfacts.htm
:http://www.a1discountprop.com/propinfo.htm
:http://www.rbbi.com/folders/prop/propcalc.htm
:http://www.csgnetwork.com/marinepropcalc.html
:http://www.go-fast.com/Prop_Slip_Calculator.htm
:http://www.fishweb.com/recreation/bo...ps/props1.html
:
:
:
:"Bob" wrote in message
...
: It's a model 270D...2.15:1 gear ratio. When the boat was brand new
: (1972) and using the same pitch prop, the top-end was always 31-32 mph,
: so I feel good that I can get there with a rebuilt engine. Will a
: higher pitched prop, say a 14x19, drop the WOT rpms? If so, how does
: that equate to a higher WOT speed? Seems like it would do the opposite,
: but like I say I don't know much about props.
:
:
: Stanley Barthfarkle wrote:
: :Bob, what model is your outdrive? Do you know the gear ratio? Seems to
me
: :that you should be able to swing a more aggressively pitched prop
(more
: :top-end speed) with that engine, but it would help to know your
outdrive
: :specs.
: :
: :
: :"Bob" wrote in message
: ...
: : I am using a standard (aluminum?) 14x17 prop, which seems to match
the
: : boat well because my WOT is about 5200 rpm, but than again I don't
know
: : much about props. I do have a Sting Ray hydrofoil but I prefer not
to
: : use it unless I am going to be carrying a large load...it surely
helps
: : me get up on plane faster, but it also reduces my top end by a few
mph
: : as well as making the steering feel "tight" and not as responsive as
: : without it. One thing that is different on my boat than many of the
: : newer boats, is that the bow is closed so I can't put passengers up
: : there, which probably does not affect the top speed, but sure does
: : impact the ability to plane quickly when the boat has more than a
few
: : adults in it.
: :
: :
: : Stanley Barthfarkle wrote:
: : : What prop are you using? Do you have a Sting Ray Hydrofoil? If
not,
:get
: : ne. Boat planes better, and it allows use of a higher pitched prop
14 X
: :21
: : :SS cupped in my case). Less cavitation, and no "rooster tail"-
energy
: :that
: : :would have been wasted with a rooster tail is sent rearward,
:increasing
: : ropulsion.
: : :
: : :
: : :"Bob" wrote in message
: : ...
: : : Dang, how do you get so much speed out of your little Volvo
engine?
:I
: : : have a newly rebuilt AQ130C ( 4 cyl. 130 hp) and it only takes my
:boat
: : : up to 31 mph at WOT, about 5000 rpm with two adults in it. My
boat
:is
: : : a 17' fiberglass v-hull and weighs about 2000 lbs I would guess,
and
: : : has a Volvo 270 outdrive on it.
: : :
: : : BTW, it consumes just 3-4 gph at cruise speed (4200 rpm, 27 mph).
: : :
: : : Bob
: : :
: : : Stanley Barthfarkle wrote:
: : : :1985 Bayliner 1952 cuddy
: : : :18.5' fiberglass 'modified V' hull
: : : :19.5' Length over all
: : : :2200 lbs dry weight
: : : :1985 Volvo Penta AQ125B 4 cyl 105 hp 4 stroke
: : : :1 barrel Solex carb 35 mm
: : : :Volvo Penta 270 Stern drive
: : : :14 X 19 modified SS 3-blade prop (14 X 21 effective)
: : : :StingRay Hydrofoil
: : : :35 mph WOT @ 4800 RPM
: : : :32 mph cruise @ 4400 RPM
: : : :
: : : :Premium unleaded fuel (92 octane)
: : : :4 adults & 1 dog, ski equipment, coolers, etc-
: : : :6-7 gph WOT
: : : :5 gph cruise
: : : :
: : : :
: : : :
: : : :"Matt Lang" wrote in message
: : : . com...
: : : : Guys,
: : : :
: : : : I am thinking about getting a harbercraft jetboat ... these
:things
: :are
: : : : made from aluminum and have the 175 HP Mercury sportjet..
: : : :
: : : : So far so good ... Now what raises the fuel warning flag are
the
: : : : terms:
: : : :
: : : : - jet
: : : : - 2 stroke
: : : : - carburator (two of them
: : : :
: : : : The boat will burn about 5 gallons per hour at 30 mph... now
I
:was
: : : : wondering how this compares to a similar sized fiberglass
hboat
:with
: : : : 115-150 HP 4 Stroke outboard..
: : : :
: : : : What is the fuel you burn at cruise speed and WOT, whats your
:boat
: : : : size/weight and what motor are you running ..
: : : :
: : : : I am interested in how the relatively light alu jetboat
compares
:to
: :a
: : : : more conventional boat with 4 stroke motor..
: : : :
: : : : Any info is appreciated
: : : :
: : : :
: : : : Matt
: : : :
: : : :
: : :
: : :
: : :
: : :
: :
: :
: :
: :
:
:
:
:

Good God!
Does anyone actually pay you for your web design services?

Actually, yes.. The page you saw was just thrown up because some friends
wanted to see the boat when I first bought it... Haven't done much with it
since throwing it up.

Needless to say, my own site isn't what I worry about.... I spend too much
time on everyone else's.

"Joe" wrote in message
...
Good God!
Does anyone actually pay you for your web design services?