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
: : :
: : :
: :
: :
: :
: :
:
:
:
: