Boat Speed Calculator

[GEOO]

BAM's Boat Speed Calculator http://www.go-fast.com/boat_speed_predictions.htm Seams pretty close to me. Type in the actual loaded weight ie. 18 Donzi 3000lbs (+-), 22 Donzi 4000lbs (+-), leave the constant @ 225 for 10-13% slip.
See how much power you'll need to go 80, 90 ect... eek!

[2biguns]

So all I need to do is upgrade to 1709 hp and I can keep up with you!!!

eek! eek!

[Barry Phillips]

My speed is on the money.

SO-SLO

[Moody Blu']

hmm my boat gps'd at 51-53mph

with those calculations my boat has 160 HP eek!

something is wrong here! :(

what do i calculate for bottom paint :o

if i put 150 as a constant it comes out to 360hp

man i guess fords really do suck wink

[Stix Magill]

I can make my numbers work if I adjust the weight to 3750 for my Minx. Do you guys think this may be an accurate weight with 2 people and gear and 1/2 tank (20 gal)? 350 mag alpha.

My Alpha SS is being installed as I type. I wonder if this will change the slip from 10 to 13 to 8-9...... if so, I may see 67 instead of 60!

[Stix Magill]

I just found that "the brochure said 2700 lbs. wet" in previous posts. Obviously, the Minx weighs more than an 18 listed above at 3000lbs. What is the real weight?

Maybe I need to find scales. Where do you find scales for this?

I am a never-ending flow of questions every time I log on..... sheesh.

Thanks,
Scott

[Rootsy]

AND for all of the 16 guys...

if i use it for my 16 given that i scaled her at 2400 with 1/2 tank of fuel and i am another 150 + say 50 lbs of gear... so a total of 2600 lb +/-

roughly 340 pshp (370 crank), 76 mph i get a constant of 210 with the alpha SS running either the cleaver or quad IV O/T which ran about 16% slip...

if i use the quad IV @ 9% slip i get a constant of 205 - 207 (74 - 75 mph).

if i go to the gen II era i get 188 using my all time best 68 mph running a cleaver again around 16% slip... i've used this constant in the past and it holds pretty constant for every iteration of hp i've done...

therefore to get to 80ish with the SS and the quad IV... i need 390 pshp (roughly 420 crank) with the quad IV and 380 pshp (410 crank) with the O/T or a cleaver... that camshaft in the toolbox at home should get me there :D

i guess this all tells me that maybe the quad IV is not the right prop and i need MORE slip to get more speed eh... but tis the price ya pay i reckon to have GOOD midrange speed :)

so how bout the 22's... :)

PS. STIX, i ran my boat across the truck scales at the local truck stop. got a total weight of it unhooked from my pickup on the scale... then i dumped the boat in the water and came back and weighed the trailer only...

[Cuda]

I input the numbers for the Formula except the horsepower, and it came out 986 horses, which is pretty close to the 450 a side the previous owner told me.

[BUIZILLA]

Stix, I plugged my Minx numbers in and it came to 3781#'s
I had figured 3740, so it's damn close.
My slippage is 8.5% though??

J

[harbormaster]

Will it work for a twin engine boat?

[Stix Magill]

Buizilla,
How did you arrive at 3740? Sounds good and seems to work with the formula. Just wondering...
One of us need to weigh a Minx.
BTW, I am....
350 mag, alpha, 23 mirage, 1/2 tank, 2 fellas, 59.6 mph GPS.

[BUIZILLA]

Stix, mine went 59.5-59.6 with just me, full fuel and 23 M+, and the bimini top on it's supports...

Might hang my SS drive this weekend if time permits. Had to put a water pump in the 18 today eek!

J

[MOP]

Want to drive yourself nuts, these are a few I found poking around tonight :D :D
http://www.rbbi.com/folders/prop/propcalc.htm
http://www.boatramp.com/prop_applet/PropAnalyzerAppletG.html
http://www.go-fast.com/Prop_Slip_Calculator.htm
http://continuouswave.com/cgi-bin/propcalc.pl
http://www.byuboyz.com/boats/prop.htm

[Stix Magill]

Buizilla,

You and I should post Alpha to Alpha SS improvement numbers for our Minx boats. This may help the other SS owners (or future SS owners)with their slip numbers.

[Cuda]

Harbormaster:
Will it work for a twin engine boat? Yes, it gives total horsepower needed for the speed.

[MOP]

Cuda I think there must be a variable, One drive 600HP is faster than two drives with 300HP each on the same boat. Weight and drag take their toll, I did a few 24 foot Priviteers years back I remember the speed diference between two 150's and a 300 Johnsons on almost identical boats (no GPS but my best guess 5 mph faster for the V8. I think the spread widens a bit with the extra weight of I/O's.

[GEOO]

I think an old Volvo needs to use a constant of 190-200. Older boat's and custom engines HP are rated at the crank subtract 10 % for prop HP. Gas weighs 6-7bs a gal. 30 gal= 210 lbs. and don't forget all the other stuff Life jackets, anchor, chain, rope, lines, fenders, extra batteries, coolers, extra wires & bilge pumps, Mufflers, Trim Tabs, etc..
I never weighed my boat, The catolog said 2400 lbs. I probaly weigh closer to 3100-3200lbs.

[Cuda]

MOP, I think the difference is made up from the extra weight in the data of the calculator.