Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Another prop seaker, New F50 on Classic 15'3
Posted by Westcoaster on 03/28/13 - 9:29 PM
#1
Hey guys
i just pulled the origional Evinrude super 55 of my hull
it was mounted a couple holes up, not sure what prop it pushed,i had it off once and couldnt get any info on pitch etc.
Anyways im picking up a new 2012 F50 Tiller model next week
And was wondering if anyone could steer me towards a prop or two, i went with the f50 for a couple reasons, i wanted to save some $ on fuel and i will also be using the motor to troll with a downrigger for salmon here on the bc coast. i guess im looking for an descent prop and dont mind spending the money to get it.
But i dont wanna buy a prop just for trolling reasons, i still wanna have some fun with this great little hull.
Gear ratio is 1.85 and its rpm is 5,000-6,000 as stated on Yamaha's website.
Another question i have is how high up would you suggest i mount it ? 1,2,3 holes or just try and get it roughly 2 " above top of transom.
Cheers
Edited by Westcoaster on 03/28/13 - 9:31 PM
Posted by Tom W Clark on 03/29/13 - 7:36 AM
#2
Mount it three holes up and use a 12" x 11" Stiletto Star 3.5
Posted by Westcoaster on 03/29/13 - 9:27 AM
#3
Thanks for the quick reply
i was wondering, you suggested an 11 degree pitch for this setup, i'm curious as to why all the prop calculators i tried are suggesting 13-14, entered values for the calculators were 50hp @ 5,500rpm, 35-37mph boat speed, 7-10 % prop slip and 1.85 gear ratio.
What really caught my attention was this thread
http://continuouswave.com/ubb/Forum1/...18267.html
He has 1987 15 Sport hull (mine is classic smirk) with a Yamaha F60 four stroke EFI which is basically the same
motor but 10 more hp, yet he is running with an aluminum prop 10 3/4 diameter x 15" pitch
and tops out @ 5,800 rpm. Does the 1 1/4" difference in prop diameter have something to do with it ?
So this has me wondering, since the setup is very similar why such a big difference in prop pitch.
forgive me as i'm new to all this prop figuring , i'm sure there are reasons
why but hope you could elaborate a bit please ?
Thanks again
Edited by Westcoaster on 03/29/13 - 9:34 AM
Posted by Westcoaster on 03/29/13 - 2:38 PM
#4
ok I'm understanding things a little better now, gonna go with what you suggested Tom.
would this work
Stiletto Star 1 Yamaha 40-70 hp 12 x 11 pitch right # 32011 3101883
Edited by Westcoaster on 03/29/13 - 10:30 PM
Posted by Tom W Clark on 03/30/13 - 7:34 AM
#5
For those reading this now, or in the future, let me point out that propellers are not generic pieces of hardware that can be described simply by pitch and diameter. Every model of propeller is different and they will not all yield the same calculated propeller slip.
Unlike a basic aluminum propeller, the Stiletto Star will typically yield a calculated slip between 0 and -5 percent. Assuming this boat can go 35 MPH at WOT, a propeller calculator suggests a pitch of about 11 inches, so that is where the recommended size comes from.
A classic 15 rigged with a tiller steer four stroke is going to have a much greater rear weight bias than a Sport 15, and it is going to need all the stern lift it can get, that is why I recommend the high blade area, low rake Star over the Stiletto Triad for this application.
Posted by Tom W Clark on 03/30/13 - 7:36 AM
#6
Propeller pitch is described in inches (a distance), not degrees (an angle).
Pitch is the nominal distance a propeller will travel (excluding slip) in one full revolution.
Posted by Westcoaster on 03/30/13 - 2:28 PM
#7
As luck would have it my current transom holes are not going to work, i could fill them and drill new holes or maybe use a jack plate, the new top holes would be around an inch from the existing ones, i have more room to work with on the bottom, they would be close to 2" apart if i make the new holes 6.5" center to center from top to bottom using 9 7/8 spacing for the bottom and 12 7/8 for top holes, i think it would work either way as i want to mount the motor 3 holes up anyways.
If i went with a jack plate would a different prop be in order
what do you guys think ?
Edited by Westcoaster on 03/30/13 - 2:33 PM
Posted by Joe Kriz on 03/30/13 - 2:46 PM
#8
Why do you have to drill new top holes?
Usually, the top holes are in the correct location.
Only the bottom holes on some installations were not the Standard.
http://www.whalercentral.com/articles...icle_id=82
Posted by Tom W Clark on 03/31/13 - 7:58 AM
#10
So, what's the problem? Plug and fill those old holes, drill new holes on the BIA pattern. See this article:
http://www.whalercentral.com/articles...icle_id=82
All large outboards made since the mid 1980s use the BIA bolt spacing, so you're going to have to drill those holes regardless of what motor you use.
Seems silly to me to spend money on a jackplate (which will also not have the right holes) when all you need is some glue and putty. A jackplate is not going to work well for a tiller steered motor even if there was a jackplate that had the right holes spacing.
See this recent discussion of the pros and cons of different ways of dealing with old bolt holes:
http://www.whalercentral.com/forum/vi...d_id=16858
Posted by Westcoaster on 03/31/13 - 10:50 AM
#11
Ok
i'm going to drill out the existing holes an 1/8" more in diameter
also planning on using West systems epoxy 105 with the 206 hardener
i will wet out the holes then use 404 high density filler to make a thickened batch of epoxy,
after its cured i'll sand, gelcoat,sand,gelcoat,sand the mounting area.
i pondered the idea of epoxy soaked wooden dowells but wasn't comfortable enough with that as all the dowells i found here are softer woods.
I am also going to use a couple thin stainless reinforcement plates maybe 15x12x8" , i just wanna try and even the load and eliminate as much stress as i can on mounting bolt locations.
Cheers
Edited by Westcoaster on 03/31/13 - 10:51 AM
Posted by Westcoaster on 03/31/13 - 11:53 AM
#13
Thanks Joe
Posted by Tom W Clark on 04/01/13 - 7:27 AM
#14
No need to make this repair more complicated than it needs to be. Here are a few points I want to make:
NEVER use dowel to plug a transom hole. It will not compress as easily as the transom so when you tighten the motor mounting bolts the dowel can "pop" the repair. Use plugs instead.
You could cut your plugs from plywood like Joe did; nothing wrong with that so long as the plywood is good, but there is no need to use plywood unless that is all you have. I would use a softwood, ideally douglas fir, because back in the day, the plywood in Whaler transoms was made of douglas fir plywood from the PNW.
Strictly speaking, it doesn't matter what specie of wood you use so long as it has approximately the same density and modulus of elasticity. Any softwood would be fine, (most types) plywood would be fine, oak, teak and other hardwoods like that, less so. NEVER dowel. Have I mentioned that before?
The transom of a 15' Whaler is two inches thick. It is made of two layer of 3/4" plywood encased in fiberglass. It is the 1-1/2" thickness of the plywood core than you want to plug with wood so just keep inserting glue covered plugs until you've filled that thickness. Do not worry about over-filling because you are going to re-drill the surface of the holes after the glue is set.
Mask the area around each hole thoroughly so you are only sanding the hole itself; do not get into sanding the whole motor mounting area. All the repair needs is to be, is flush and fair with the surface. Once the motor is mounted, the repaired holes will be completely covered and invisible.
There is no loss of transom strength. Use a backing plate if you like but Whaler transoms are much stronger than most people realize.
Posted by Westcoaster on 04/02/13 - 6:56 PM
#15
I was able to clean up the the prop from the old motor and read it this time,13 & 1/4 x 17 aluminum,motor was a early 80's 55 Evinrude 2 stroke ( commercial model), it performed well.
What do you think Tom ? Would this change what you think i should try for prop size on the new motor, i know the two are quite different but just wondering with this new info and all.
Thanks again i really do appreciate the help from you guys !
Edited by Westcoaster on 04/02/13 - 6:57 PM
Posted by Tom W Clark on 04/02/13 - 7:50 PM
#16
No, your old prop will not going to work. Gear ratios and RPM ranges have a HUGE effect on what propellers you can use.
Though a 55 HP Evinrude two stroke from the 1980s has about the same power as a Yamaha T50 four stroke from 2012, they will use very different props on your boat.
The hub of the old OMC prop won't even fit on the Yamaha T50's propel shaft.
Posted by Westcoaster on 04/02/13 - 8:10 PM
#17
Using the old prop never even crossed my mind, i just figured knowing how it was proped before may help thats all, i ordered the 12x11 Stiletto and will break the motor in as per Yamaha manual and see how it works out after the first 10 hrs
Hopefully picking up the motor on thursday, chompin at the bit here...
Edited by Westcoaster on 04/02/13 - 8:14 PM
Posted by Westcoaster on 04/07/13 - 8:50 PM
#19
Ok back to the mounting of this motor, with the new motor home now i measured and remeasured everything, i only have 8 1/2" on the inside to work with, from the top cap to where i'm comfortable puting a bolt through, i also read all the faq's from continuouswave on mounting options for shallow splash well whalers/montauk's, lots of information there for sure but the fact remains i don't have many real good options.
I am not going to drill the bottom holes on an upward angle from the outside, something is just not right about that. The best solution seems to be using a spacing of 6 1/2" on center between top and bottom holes, but my mounting options would be limited to 2 or 3 holes up only.
I would have liked to use a spacing of 7 1/4" which would allow the motor to be mounted anywhere from one hole up to 3 holes up, but i just don't see me having the room, i would have to move the top holes closer to the transom cap, they would need to be less than 1 1/2" and then drilling on an upward angle aswell.
How close to the transom cap is too close anyways ?
There is nobody professional around here i would trust with this job, thats why i'm just taking my time patching things up and trying to just do it once the best way possible.
The main reason i would like to have mounting options from 1-3 holes up (7 1/4" spacing) and not just 2 or 3 holes up (6 1/2" spacing) is the fact i plan to mod my f50 to an f60 at some point.
i realize this would mean dialing it in all over again with props etc. and thats fine im just tring to avoid not being able to lower the motor if need be.
But if you guys figure an f60 would end up being mounted 2 or 3 holes up then i'll drill away with 6 1/2" spacing.
I could try for the 7 1/2" spacing but i'm really not interested in having to cut washers in half or bend backing plates etc. but...
Edited by Westcoaster on 04/07/13 - 8:53 PM
Posted by dgoodhue on 04/09/13 - 9:35 AM
#20
You will only need the 2 or 3 hole up positions.
Posted by blacksmithdog on 04/09/13 - 3:13 PM
#21
So, my Yamaha F50 is sitting all the way down on the transom, it is obviously too low. What is the proper relationship height wise of the cavitation plate to the bottom of the keel on a 15' Whaler?
Thanks
Posted by Westcoaster on 04/09/13 - 10:29 PM
#22
From what these guys have told me minimum 2 holes up, preferably 3, there many things to consider, stay tuned and i'll let you know how mine works out 3 holes up, definately higher for 4 strokes,i do have a new motor and need to break it in properly first. What kind of setup do you have ? What year hull, center console, side helm, prop pitch etc. ?
How does yours ride right now ?
Handling, planing etc ?
Edited by Westcoaster on 04/09/13 - 10:34 PM
Posted by blacksmithdog on 04/10/13 - 4:43 AM
#23
Mine is a 1992 15' GLS, I guess you'd call that a side console.
I'm running a stainless 10.5X12 prop, I think it's a Yamaha.
I get around 5500 rpm's if I play with the trim, and with two people in the boat.
It does 32-33 mph per the GPS.
It seems to come out of the hole slowly, and not plane quickly.
Posted by tedious on 04/10/13 - 4:46 AM
#24
blacksmithdog wrote:
So, my Yamaha F50 is sitting all the way down on the transom, it is obviously too low. What is the proper relationship height wise of the cavitation plate to the bottom of the keel on a 15' Whaler?
Thanks
It depends on the prop. If you're running a decent, modern stainless steel prop (and you should be) I would start with the AV plate about an inch above the keep line, and see how she goes. That will probably be either all the way up, or one hole down from that top position.
Tim
Posted by Westcoaster on 05/06/13 - 3:21 PM
#25
Finally had the boat out for a sea trial and break in procedure,
i spent quite some time repairing old stuff i been meaning to clear up, also reconfigured the deck layout etc,
12 gallon gas tank up front, battery on port side 6' from stern and was able to move my seat forward better than a foot all to compensate for the heavier weight of the new 4 stroke, also new wiring, fuses,bilge,battery,fuel tank & hose and nonskid paint.
Once launched i noticed it sits very nice in the water, not stern heavy
break in procedure calls for 2,000 rpm in the first hour or about half throttle, second hour says increase throttle enough to put on plane then back off and maintain plane. i had nothing but problems finding out how to wire a round yamaha tach with the tiller handle, the needed hub is being used by the manual rpm adjustment in tiller, , I called Yamaha Canada and USA aswell as many service centers and got nothing but conflicting part #'s and procedure, NOBODY knows how this is accomplished ? so opted for a cheepy from yamaha, the kind which wraps around spark plug wire which i now know is inaccurate, shows 1200-1500 at idle and around 4,000 at half throttle. Very dissapointed as i would like accurate rpm.
Anyways i just used the throttle position indicator on the throttle grip as my reference, half throttle put me on plane which was surprising to me, so i just backed off a little to maintain it, this was trimmed all the way down or in, boat speed was 22-24 mph on gps, after the first hour i increased speed about another 1/8 - 1/4 and ran it for another 45 mins varying speeds slightly between 25-30 mph, 30 mph was under 3/4 throttle and bow stayed down nice and steady, then i played with trim a little, i can't trim out very far before cavitation starts, i had a couple quick looks down at the leg while cruising and could easily see the anit ventilation plate above the prop, although its hard to determine if the rear of plate sits above water and by how much, i am using the Stiletto 12x11 recommended by Tom, seems to be a good fit from what i can tell so far, the stern lifting ability of the prop worked better than expected, but then again i only weigh 175 lbs and the boat is well ballanced now.
All said and done i was very surprised how easily the boat planes but worried about the cavitation, the boat seems fine trimmed all the way in or a hair out, next trip i can run WOT for short intervals.
We will see how the next trip goes and decide if i might want to change the mounting position, its 3 holes up now ( highest position for the 2013 50HP Yamaha 4 Stroke LHB)
my first post indicated a 2012 but ended up with the 2013
just figured i would clear that up.
Edited by Westcoaster on 05/06/13 - 3:40 PM
Posted by dgoodhue on 05/06/13 - 8:17 PM
#26
You probably don't want to hear this but I think you have too much weight forward. I have this problem if I have too many passengers in the front. IMO the 15' like the weight rearward. (or atleast in the stock position). The static might look perfect but the best weight distribution for.performance isn't always with a level static trim.
50hp 4 stroke is no heavier than any of the 2 stroke 70hp motor the boat was designed for. If your fuel tank is movable try temporarily putting that in the back to see how you boat responds.
Posted by Tom W Clark on 05/06/13 - 8:41 PM
#27
I have yet to hear of anybody needing to lower a motor with the Star, but maybe a 15 Standard is one example of a set up that needs the motor a little lower.
You are really going to need a tach (at least for initial testing) to figure out if the pitch is correct or not.
Posted by Westcoaster on 05/09/13 - 10:18 PM
#28
Yup i'm gonna have to lower it it some, was out again this evening
Flat calm, can't trim out at all, tight turns causes cavitation aswell,
WOT put me @ 33-34 mph trimmed all the way in.
What does it sound like when you hit the rev limiter ?
Don't think i hit it but just curious
Edited by Westcoaster on 05/09/13 - 10:22 PM
Posted by tedious on 05/10/13 - 5:04 AM
#29
I'm with Dave - I think you've got a good deal too much weight forward. You mention you did that to compensate for the greater weight of the 4-stroke, but your F50 weighs 249 pounds, actually a bit less than the classic OMC triple that many of the 15s were originally powered with. If you're ventilating so badly so you can't use the trim at all, something very basic is wrong.
I have not seen the pictures of your setup - what can you easily move back to give that a try?
Tim
Posted by Westcoaster on 05/10/13 - 3:57 PM
#30
Ok first of all i want to point out i appreciate all the feedback, info and suggestions, love this site.
I googled the serial and model from the motor i pulled, i could not find a match for that model but the closest ones were around 195 pnds, it was an early 80's Evinrude (super) 55 Commercial Model CE55RSLV, definately lighter than the new power as i just pulled the bolts and lifted it off myself ( i weigh 175 )
Besides the motor these are the things i changed
battery used to be tucked behind my seat on the rear starboard,
It now sits on the port side 6' or so from stern.
I used to pack two 6 gallon tanks which sat mid deck, one port and one starboard, now i have one 12 gallon fastened to deck right behind the bow locker.
Moved my seat forward 12" or so
Thats it for changes
For the first few trips i never had the gas tank full, maybe 8 gallons to start with, but lastnight on my way in i only had a couple gallons at most but still had the cavitation.
I will upload a few pics of the setup in a bit, although i never took a picture as it sits in the water but will get some next outing
Sure like to get things figured out
Edited by Westcoaster on 05/10/13 - 4:54 PM
Posted by Westcoaster on 05/11/13 - 10:24 AM
#32
i will try running it with the fuel tank at the stern but the more i read the more i'm thinking its simply just mounted too high, i can actually see the air being blown out the back under the anti ventilation plate when i try trimming out. I do have another prop to try but hope to get this one dialed in.
Posted by Tom W Clark on 05/11/13 - 10:38 AM
#33
I doubt you have too much weight forward. I think the motor is too high for that propeller.
You are suffering ventilation, not cavitation. The Star has a large diameter so the blades tips are going to break the surface more.
I'd lower the motor one hole and see how it does. I would not spend money on anything else until you play with the mounting height, but it is important to get a tack, even if only renting a diagnostic tach, to get the WOT RPM.
Posted by Westcoaster on 05/11/13 - 2:57 PM
#34
Oh i didnt know i had the option to rent one, how do they normally connect ? I still can't get over the fact that nodody seems to know how to hook up a permanent accurate tach to my motor, its driving me nuts.
I'm in a small community and finding anything of use here is dam near impossible but i will try again as i realize the importance
Edited by Westcoaster on 05/11/13 - 2:59 PM
Posted by Tom W Clark on 05/12/13 - 10:53 AM
#35
Diagnostic tachometers can use optical (laser), infrared, or acoustic signals. They do not necessary connect to the motor at all.
The difficulty with them is you need to run the motor with the flywheel exposed, so it may be awkward or dangerous to try using one.
Why can't you just unplug the trolling speed control to temporary plug in a tach?
While your digital tachometer may be inaccurate, it *may* be precise. In other words, if it is off by say, a factor of two (which is my guess) you can still use it but know you need to divide by a constant to get your true RPM. My guess it is simply measuring twice the true RPM. What did it read at WOT?
Posted by Westcoaster on 05/12/13 - 11:35 AM
#36
Digital read around 8,500 but will have to have another look to confirm, i have emailed Yamaha Canada and US again asking for some assistance and just waiting to hear back, thats a good idea unplugging the rpm controller, problem is i don't have the tach or any harness, i should be able to get this figured you would think, there is a multi hub connector aswell so i should be able to have both working together, just wanna confirm before i purchase, i will try changing the # of wraps around the lead wire with the cheapy aswell and see how that goes.
Edited by Westcoaster on 05/12/13 - 11:49 AM
Posted by Westcoaster on 05/13/13 - 2:13 PM
#37
Motor is now lowered to 2 holes up position
I am actually making a little progress on the Yamaha tach aswell, seems there is tiller handle for Canada and a different one for USA, Canadian version requires a mod before the tach can be fitted,
still waiting to find out what the mod is.
It will be a few days before i can go for another test run
Posted by dgoodhue on 05/13/13 - 2:50 PM
#38
I looked at your pictures. Running alone you shouldn't have any weight issues. I bet dropping the motor 1 hole or changing to more toleran surface prop will resolve your issues.
Posted by Westcoaster on 05/23/13 - 1:00 PM
#39
Was out on the water again lastnight for the first time since lowering the motor one hole, dropping one hole made a bigger difference than anticipated.
I was able to trim out enough to make the bow rise and increase speed an extra mph or two, i think its still slightly high but will put some hours on like this, i cannot drop the motor anymore as the spacing from top to bottom transom holes are drilled with 6 1/2" spacing, my only other option is to drill holes in the motors lower mounting plate 3/4" above the top of existing lower bolting slot.
I will do more testing, it was pretty choppy lastnight but i was able hit WOT a couple times tucked in behind a small island, i saw 35+ mph a couple times.
I thought i was making some ground with Yamaha lately trying to figure out how to mod my tiller handle to accept an accurate Tach, they have stopped returning my emails. The cheep tach a have wrapped around a lead wire is unreliable, at idle it shows 1,00-1,250 with the throttle backed right off, my motors manual says the trolling idle is adjustable between 600-900 rpm using the buttons on tiller arm, i can adjust idle up to the point where my tach reads around 1,300-1,350, then pushing rpm up button dosnt do anything so i know i'm around 900 actual rpm.
However at 25 mph cruise on gps the tach reads 4,800-5,500, WOT was more inconsistant, first time i hit wot tach read 5,500, second time it jumped to 6,700 and never bothered to look after that.
So since i am able to hit 35+ im asuming i must be close to the right propping and mounting height, without accurate rpm i just cant be sure but has to be close i would think, although i think if i could trim out just a little more i could get 37 mph out of this motor.
Posted by dgoodhue on 05/23/13 - 7:15 PM
#40
I think your spot on for what I would expect from a 50hp motor on classic 15'.
Posted by Tom W Clark on 05/23/13 - 9:16 PM
#41
If you are exceeding 35 MPH you are already doing better than I predicted you would.
There is no reason for the motor to go any lower, but I do find it interesting (and enlightening) that the one hole made that much difference.