Page 10 of 11
Posted: Thu Jul 19, 2007 11:16 am
by bscott
Compromise..check the oil in your lower unit. Low or no oil could cause your engine to stop/start at lower rpms.
Posted: Thu Jul 19, 2007 12:56 pm
by tangentair
Andy26M
Thanks, that nav quiz program is just the ticket, I got cocky and ran the advanced inland, now I review it with my son a little more humbly.
Ron
Posted: Thu Jul 19, 2007 7:49 pm
by Bill at BOATS 4 SAIL
Chapmans
Posted: Sun Jul 22, 2007 5:47 pm
by aya16
Brian I just pmed you it doesnt sound good...
Posted: Mon Jul 23, 2007 4:51 am
by tangentair
I tried to do some test runs this weekend but the two foot waves and resulting spray annoyed the crew, still I did get two WOT runs.
manual for a 50hp Merc says redline 5500 to 6000, I got 5900
avg speed on a no mast, without ballast lightly loaded M, dagger board down 1/4, rudders up - was 15.8 mph per GPS. (it is the slower white model M)
Correct me if I am wrong but changing the prop from a 10 to 12 will lower WOT rpm and improve low end 2500 to 3000 rpm handling and motoring without serious consequences.
Posted: Mon Jul 23, 2007 6:25 am
by James V
Please do not run with the dagger board down in speeds over 7 mph and any rudders as well. It can cause the boat to heal very badly and break the boards and rudder(s) at high speed!!
I have an '06 50 HP BF with a 14 x 10 SS prop. My top speed in glass conditions with mast up and no boards down was 17.5 (for 5 hrs). Lightly loaded. RPM's 5250. Never got any higher RPM's at sea level. Marine Max installed the engin and does the work on it. Now fully loaded pulling a 130 pound dinghy I get 5100 RPM's and about 16 mph in dead calm.
I do get a chance to show off at the fuel dock. It can be a real show waiting. The other sail boats do not have a chance nor do the single engin outboards. I can spin circles around them.
Posted: Mon Jul 23, 2007 9:00 am
by Pacamac-uk
I've been following all this talk of the correct propellor, etc, in various places on this board for a while now and whilst I understand the general principles of getting the right prop for maximum power/revs I am stumped by one thing.....What is 'WOT'
I haven't found or have missed an explanaton of these letters.
Can someone oblige?
Thanks
WOT
Posted: Mon Jul 23, 2007 9:15 am
by Andy26M
WOT = "Wide Open Throttle"
- Andy
Re: WOT
Posted: Mon Jul 23, 2007 9:24 am
by kmclemore
Andy26M wrote:WOT = "Wide Open Throttle"
- Andy
As opposed to
"w00t".
Posted: Mon Jul 23, 2007 11:27 am
by Catigale
To elaborate a bit - when you buy a motor the manufacturer will provide you a spec range of rpm at which, when the throttle is advanced fully (Wide Open Throttle or WOT for short) , the engine should run.
If you cant reach this rpm at WOT, either the prop or the load on the boat is incorrect - likewise if you exceed this rpm your prop is too lightly pitched for the boat (or your engine is grossly overpowered.)
E.G. my 2003 Mercury Bigfoot 50 HP EFI has a WOT range of 5500-6000 rpm per Mercury.
Posted: Mon Jul 23, 2007 1:17 pm
by Pacamac-uk
Ah.....simple when you know!
Thanks guys
(I bet I wasn't the only one who didn't know that!!)
Posted: Mon Jul 23, 2007 1:54 pm
by bastonjock
Pacamac-uk wrote:Ah.....simple when you know!
Thanks guys
(I bet I wasn't the only one who didn't know that!!)
it took me a few threads before i figured out what wot meant
its these yanks me old mate the dont speak the lingo real proper like
BTW (by the way) have you tryed sailing up the high atreet with all this rain?
Posted: Mon Jul 23, 2007 3:10 pm
by tangentair
I have tried running at speeds over 6 without the dagger down about 1/8 to 1/4 and the boat gets a bit squirrelly in any waves or chop and if I turn across the wind it rolls over like ...well I will skip that metaphor, but with just a little bit of blade it tracks well. It also helps deal with the the roll from the prop. when doing low speed manuvering by gunning the engine.
Say What?
Posted: Mon Jul 23, 2007 5:29 pm
by pokerrick1
Posted: Thu Jul 26, 2007 2:23 pm
by Pacamac-uk
Fortunately I live 20 miles from Gloucester (Gloster) up on the Cotswolds so didn't have to do an impression of Dr Foster with or without boat!!
For those that don't know the rhyme:-
Dr Foster went to Gloster in a shower of rain,
He stepped in a puddle,
Right up to his middle,
....never went there again!
My son works adjacent to the flooded water treatment works in Tewkesbury and now has no mains (town) water and expected to be so for 2 weeks or so. He now comes home 40 miles to shower!
Seriously the flooding is very extensive and up to 350,000 now said to be without water. Luckily the Navy saved the power substation and kept the lights on......a little bit of water dosen't stop 'em.
