Prop advice...

[James_V17L]

Hi everyone,
I have a V17L with a 115 yamaha(precision blend early 90's)
It seems to lack a little top end speed.I know bugger all
about props & I would appreciate any advice.
Not sure what prop is on it..the only markings are "17-K"
Thanks everyone..

[NQCairns]

James how many RPM are you doing when flat out?

[James_V17L]

Thanx nq for the reply,
She cruises pretty good at around 4750 & revs to about
5200-5300 flat out..but seems to be workin pretty hard
for the extra knots.
I havent had the boat for long so I am still in the process
of getting used to it.
One thing I have noticed is the engine has been moved
up about an inch from its previous position.
Its very touchy on trimming,seems to pick up the rpms
but goes no where & gets very "porpoisey"
I am beginning to wonder if the engines too high & the
prop isnt the problem...the main skeg rib(where the stingray
is attached)is about 1" above the bottom of the transom.
It seems strange that if the engine was dropped down to
its previous position it would be basically be in line.
I guess too, the stringray is another subject???

[blaze]

Hi James
If she was mine, i would take the stingray off and drop the motor to level or a touch under and start from scratch. try the boat with the moter in that postion, the fin will take some top end away. I would think that the prop you have is a 17" pitch which sounds about right, not sure on the top revs though, they seem a little low
whats the hole shot like
how loaded is the boat
test the boat unloaded for a start, 50% fuel
keep up the questions
cheers
blaze

[James_V17L]

Thanx Blaze...excellent advice.
Last trip..fully loaded with fuel,the wife & 2 kids.
The boat is a little slow to plane..
I am gunna try what you suggested & give her
a run this weekend.
Any idea what the "porpoising" could be caused by?
I used to own a V17L years ago with a 135 V6 Black
Max on it & it performed awesomely,so I have a fair
idea how these hulls perform.
Again thanks,I appreciate it...James

[NQCairns]

Hi again, my advice differs a bit from Blazes, the higher a outboard is set the more efficient it runs(less drag), one hole up on such a deep running hull is fine, if it were a low deadrise hull then closer to the keel line could work better. The water rises very fast after exiting to meet the leg on deep running hulls even at speed.

If it were mine and the hull is in spec, I would throw the foil like blaze says then fit a 2 inch lower pitch prop same diameter, this should grab an extra 400 or so RPM to put you in a better range for hole shot and throttle response at speed etc just better all round.(you could even go up 600 ;D)
Testing should be done with full load or most typical load always, any extra rpm gained when running light is a bonus for the trip home etc and still way within the real world operating range of the engine.
Porposing is caused by not enough bow lift-AT THE PROP ONLY ie it maintains bite the slips dropping the bow then grabs again then slips, adjusting weight is treating the symptom not dealing with the cause. Another way to promote porposing is to lower the leg and create more drag the prop has to overcome before losing grip and dropping the bow.
It sounds like you need pep! 400 rpm will give yyou pep, the leg height should helps overcome porposing and hopefully the extra thrust when proprd right will keep enough bite to eliminate all hint of porposing.
Probably too much info ::), good luck.nq

Edit: just searched up your leg ratio(if I got the right engine) it is strange (low)and probably the reason you noticed the 17 not doing the job, good call.

[Big_Kev]

Pull that foil off and give it to someone you don't like.
I agree with Blaze and NQ and think to change the prop out is a simple option first. I would only go to a 16 but. Then you could try to drop the engine a bit, but that is a bigger job.

[James_V17L]

Awesome info guys I really do appreciate it.
NQ..About the porpoising when I think about it
you are 100% correct..I can actually feel & hear
the engine "losing grip"..now I understand it better.
Anyone got some props??
Guys,am I attacking this the proper way:
Try this all on the same day:
1: Run the boat as is to get a baseline
2: turf the stringray & have a run
3: change the prop & have a run
4: re-fit the old prop & drop the engine & have a run
5: change back to 2nd prop with engine dropped & run

I guess this should tell me a few things??
Thanx guys for your time.

[NQCairns]

Hi James, ring someone like solas and try some ally props, hopefully they should allow you to test a few.

The reason most people exclaim how great SS props are (unless racing). Is because for the same specs, the SS prop because of their fine and rigid nature actually run on the water up to 1 inch lower then the same spec ally prop. They then say wow I gained 150 - 200extra rpm and 3km/h. It would have been achieved with a one inch lower ally for less cost and have been kinder long term to the drive train as well, just food for thought, so you dont get sucked in for the extra $.

Rule of thumb 1 inch up or down = approx 200rpm lower or higher.
A 2 stroke running typical fishing load and running 4800 - 5100rpm forget about it it is a dog on the water.
5100-5400 lazy but useable.
5400-5650 just acceptable performance/speed/fuel econ/handleing
5650-5900 best performance/speed/handleing/longevity although fuel economy can suffer (slightly) at the higher end of this WOT range when at cruise depending on prop brand/style.
I like your list although unless you have exhausted all your prop choices dont drop the engine there is nothing to gain and everything to lose by doing that 90% of the time.
If when you gain your chosen RPM/prop with the engine where is and you find unacceptable problems with sharp turns at speed or a lack of control in a following swell or excess ventilation on hole shot then go down a hole but do it with the prop that worked best with the engine up.
Personally I would be aiming at 5800 loaded I like a rig that says "how high" when I say jump ;D
Regardless whatever you get will be better than what you have now it seems, such a waste of a great classic hull as it stands.
Good luck, nq

PS Dont go thinking that when you prop higher your cruise RPM for speed ratio will be corespondingly higher. Badly proped as it stands now you may be geting 20+% prop slip at cruise, when efficiently proped your slip may reduce to #around 10% or less? at cruise, you may even find yourself doing less RPM for better speed at cruise. That is one of the tests you need to do with each prop tried. hope I explained that properly (no pun intended) ;D cheers.

[Hagar]

G'day James
You are in luck . I am currently running a V17L with a Yammie 115 ( 1999 model though ) and I reckon I can give you some food for thought on your problem .

Do not throw the stingray away just yet . I have rebuilt and setup a few boats over the years and I found my 17L did not have enough nose down trim available without the foil . The rake angle on the transom is not as moch as some hulls and the yammy may have a different trim range - not sure on that one . All I know is the nose down trim seemed more with the old Johnno that was on it .There was times when it needed more nose down trim going into chop etc. Since the foil was fitted it now has excess trim both ways - you never use it to the trim limit either way.
The foil has not given the boat any real vices and it comes out of the hole much better and planes longer at slow speed . It will cavitate the prop totally with excess nose up trim though especially in turns .

Make sure the prop is stainless not alloy and the cupping is still OK . Mine does 43 mph on the gps at wide open throttle and 5500 -5700 depending on load but who drives this fast anyway . The cav plate is set level with the bottom of the hull. I agree with previous posts that rpm at the upper limit is far better than being over - propped . Most mechanics will agree.

If it is porpoising then I would say it is trimmed too far nose up or the load is way too far aft . The bum of this boat is narrow and will not carry as much load aft as a lot of other hulls . I can make mine do this but it is not a trim I would ever intentionally use .

I will get the size off my prop for you and post a pic. of the motor height if you like . Busy as so may take a few days.

Chris

[James_V17L]

Thanx nq & Chris..your info is invalueable.
That pic would be awesome Chris..thanx.
I have managed to aquire a 15 & an alloy 17
to try.I still reakon the motor is a little high.
I got some water testing to do..& I am gunna have
a fat time doing it..
Again thanx to everyone,Cheers James

[skippa]

G'Day James,

I'm running a V17R with 115 Yammie and here's my 2 bob's worth. Yammies' '94 saltwater with 19 pitch SS prop and SE Sports foil. Ok the R is lighter than the L so I reckon I'm getting away with the higher pitch prop. Mostly only 2 blokes, so the 'ol girl is never heavily loaded. She will still WOT at 5500/5600 trimmed out properly. Cav plate level with bottom of hull.

I would go with Hagar, keep the foil for now. (you only got 2 choices anyway) These hulls are great rough water boats for their size and the transome is narrow and deep, so it doesn't hold a lot of weight. This is where I feel the foil helps on this hull. Mine will stay on the plane at low speeds with that deep Vee hull working just a treat. The foil might take a few K's off the top end, but who drives around WOT (and who's got the money for fuel at those speeds anyway).

The v17's matched with a 115 whatever is a great little boat and we've had many a trip back from Moreton with bigger tinnies happy to stay tucked in behind.

V17L, good choice.

Cheers,
Tony 8)

[Hagar]

Hey James
Pic of cav plate height as promised . Just like Skippa says - level with the bottom of the hull . I think you will find this is the optimum height for this hull , especially with a foil fitted . As he says a great little hull in the rough stuff . If you move the motor make sure you use good sealing on the motor mount bolts - biggest cause of transom problems .

Chris

[James_V17L]

Holy $heeett..my outboard is 1"-1 1/4" higher than that.
Thanx so much for the pic...a massive help.I will drop
the outboard first & try...what prop you running Chris?
They are great boats skippa..this is my 2nd 17L...should never
have sold the 1st one..!!!
Thanks so much everyone..

[Hagar]

James
My prop is yammie stainless 13 x 17 - K2 . I think the K2 bit means something to yamaha but not to me . Just in case you havn't done it before its stamped on the front of the prop but you have gotta pull it off to see it .

Chris

[Cheech]

James,

Looking forward to hearing the results. I am in a similar situation in trying to set my 5.5 Mustang. Is similar size.

My outboad is about an inch lower than Hagar's. May now consider raising. May help to lighten the steering.

My problem at the moment is that I cannot get my old prop off. It is jammed on. Been told by Holt Marine that they may have to burn it off, starting by melting the rubber. Sounds great,, not.

Currently running a 21pitch so will go to either a 17 or 19.

Trim can make a big difference. I initially trimmed it similar to my old tinne, but then after getting it right, I gained an extra 5km and 200rpm.

Cheech

[James_V17L]

Hi Cheech,
I cant wait to test my boat..I had to drop the outboard
2 holes to get it near where it should be or I hope where it
should be...There's some real helpful people on this forum who
know their s$heet..thanks guys.
I will post the results after next weekend..also taking some
different props with me..should be interesting.
Cheers,James

[Hagar]

James
Bump back to the top so it doesn't get too far back .Await report .
Chris

[James_V17L]

Thanx Chris,
The weather looks crappy this weekend,but I am still
gunna take her for a run sunday am...wont be doing
any prop changes..just gunna try her out with the
outboard dropped..
Again thanx for your help & thanx for everyones help.
Cheers,James

[James_V17L]

I am ONE happy camper...I cant believe the difference.
I finished up dropping the engine 2 holes.
Its a different boat..handles better,no porpoising,
better out of the hole..& no cavatation.
A big thank you to you guys...I am wrapped.
There was far bit of rough stuff around the bar
so I gave her a real good test out.
Gunna leave as is...same prop..she'll do me..

[blaze]

Good to see that you received the results you wanted/needed
cheers
blaze

[yockman]

Absolutely top A1 thread!!!!!

(From someone with a few minor prop issues atm)

Cheers,
Yockman

[Hagar]

James
Good news man . This boat deserves to be setup just right so it performs to the best of it's potential . Makes you wonder how many other boats have been given bad wraps thru bad setup doesn't it . You will probably now notice your boat will have a more narrow range of useful trim at around 1/3 to 1/2 nose up . Beyond this it will most likely cavitate the prop especially in turns . Trim the nose down a little and throw it into a tight turn at speed - it's like it's on rails . [smiley=smug.gif] [smiley=smug.gif]
Chris

[NQCairns]

Yeah good job james, it must have been cavitiating badly right from the start, go find the old owner and give him a 'thwack' ;D what was he on about, surely it was his setup? Are you going to deal with the revs? you have some spare props to try.
Hagar you really do sound like a man who owns the boat he skites about, half your luck to have such a good hull sitting in the driveway. cheers nq

[skippa]

G'Day James,

Mate glad to hear you got the setup right. These little hulls are a classic and I reckon it's a crime to stuff 'em up with a crap setup. I'm with NQ give that previous owner a good uppercut.

BTW, did you keep the foil? As I said mine loses a bit of speed at WOT, but the benifits of low planing speeds outweigh that.

Chris, your right about the turns, mine will turn on a ten cent piece.

Catch you guys on the water.

Cheers,
Tony 8)

[James_V17L]

Hi guys,
Thanks again for all your input.I still cant work out
why the engine was so high??? Doesnt matter anyways
fixed now..the guy I bought it from was a super nice
guy so I am guessin someone else has given him
some bad advice.

Blaze,I am wrapped with it ...thanks

Yockman,these guys are great,I hope these some
good pointers for you.

Chris,you are 100% correct,not much of a trim window,
cant wait to take the kids tubing again..he he..thats
after I get a few more fishing sessions in.
Sure does make you wonder about bad set-ups..

NQ,
not sure about giving him a whack..lol..hes got
shit loads more money than me..prolly sue my ass off
ha ha ha..I am pretty happy with now it is..revs to
about 5500-5700 flat out & really gets going from about
5000 on...& stills cruises nicely at 4700-4800..I have some
other props I mite try at a later date.

Tony,
Kept the foil on..I do agree these hulls seem to benefit from
the foils..as i say,I am happy with it as is at the moment.
I gotta agree 100% they are a great boat...