Prop selection help

[steve harney]

Hi All
I looking at getting a replacement prop!! I have a Hairnes Hunter 146 & a low hour 90hp Yamaha with a K17 S/S which I think is the standard prop!!
I have got some conflicting reports which way to go. I talked to Steve at Solors and he recommended at 13 1/4x17 wider blade area?? I almost fell of my perch at the prices. Now when I went into a Yamaha shop to pick up some oil I asked about props, I went through how the boat goes & & said they sell the standard props for 1/2 the price of solors and recommend a smaller prop because he said it sounds like it is over proped ok ok which one?? he said that he wouldn't put a Yamaha prop as they don't work that well & started going on about a Solo 4blade S/S is the only way to go, are well walked out & drove up to another boat place & went through it all again & he said that the engine is too small for the boat underpowered for the boat I was thinking it's the other way around walked out thinking that the motors going to blow up & I'll need a new engine!! far out!!
Well I give you some figures & maybe some good people here may be help me in getting close to the right one & not spending a pay packet on something I go fishing in!!
I lifted the motor until the Cav plate is just out of the water & trimmed out about 3/4 way & it's about 60ks on the GPS at about 5000revs which seems to be flying along nicely it doesn't feel like it can go up to the 5,500/800 max revs it got a sweet spot about 4,500revs which steering is easy and feels like just cruising A few of the fellows said you need to get to WOT speed take the figures & get a prop to suite. I know it's a heavy boat & I'm thinking it's over propped & as the boat guy said doing damage lugging it around?? Have anyone got any good idea's or what they have done & the results any help would help as said before everyone has advised differently
Regards Steve

[Bros]

I can't help you on prop size but you should be aware it is an art to select prop size not science.

I found out when I built a 10 m Steel fishing boat and went to a foundry that makes props and an old bloke gave me the exact size prop by the size and description of the hull.

[Fed]

A 90HP on that boat with a standard 17" prop should be revving its tits off.
Are you carrying a huge amount of weight, somethings not right, maybe you're down on power. I'd think you'd be good for at least 70 KPH.

[dreemon]

they were right to tell you to get your 5,500 rpms, your fairly close to where you need to be.
I've got a yam 90 with the same prop K 17 ( mine might be 13 1/2 d ?) but not sure, but I get my 5500 and gps is 64 kph max ! , 4100 -4200 sits close to 50 kph and is a good cruise speed,

Is your prop cupped much? if not you'd want something like a 16 p if they make em then cup to fine tune the revs, my kids are only going to get bigger and heavier so in time I'll have to drop in diameter too and adjust with cupping

I'm thinking a wider blade surface will only drop rpm's, am I right? FNQcairns? Cheers

[Fed]

Dreemon wouldn't your boat be a fair bit heavier & have a much larger wetted surface than Steve's 146 Haines?

[FNQCairns]

dreemon is right extra surface area is a waste, the dumb props sold of the shelf often have lots so they cover all the bases a person might reasonably use a boat for but probably never will.

The extra bades impact area of a 4 blade is also a waste, pure physics says so over 3 blades, never come across a fishing boat that works better with 4 always it's a lack of experience but never realised even if they tested others. Boats that travel fast enough to surface pierce are nice with 4 blades and so are barges, displacement hulls and freight tankers.

Anyway, try the yamaha 17p aluminium to get benchmark test figures, they are a relatively cheap purchase, very little cup to rob your HP and fuel tank of fuel and you don't need a SS, your prop will never spin fast enough for the physics of SS's edge thickness and lack of flex to make a measurable difference.

i have the same engine on a 6.2m tinny and run a modified 14p alum in heavy offshore trim, when it was lighter during it's buildup it would push the 17p and when fitted out but in estuary trim a modified 16p mercury SS, those engines are relatively low in torque (compared to older 90hp engines not today's new ones) so straight away hate lots of propeller surface area.

[dreemon]

Hi Fed, I have the Jeff Websters secondhand boat secrets mag, it says the specs on the hainses hunter 146c are:

Length; 4,42
Max beam ; 2.06
Deadrise: 20 degrees
Hull weight : 364 kg
weight on trailer ; 750 kg
max power; 70hp
best power; 70hp


Mine, Naughtiglass sportsman V-150

Length; 4.60 . .. . . . . . . .. . . . . . . 4.85 with S/S bow sprit ;D
Max beam; 2.0
Deadrise ;12 degrees
hull weight; 355 Kg
weight on trailer; 750 kg
Max power; 85hp
best power; 60hp

also in the mag it mentions alot and both of these boats are seen with the yam 90, and like FNQ says the power of these yam 90's are diff to what used to be on them in there days, mine came with a Johno 85hp V4 and Farout did it boogie ! ! ! :o and chew fuel like the yesteryears too aswell as heavy,

took mine out today and 4300 rpms sits on 50 kph,

when we got back to the boat ramp at southport the jettie sepperated into two and when my wife had to leap for her life she tripped over and did the slowest tumble I Have ever seen, my 9 yr old boy said it first, she's allright,

BTW , we got the jettie back together again

Steve I wonder if it might help it you lift the engine up anouther hole?
Cheers

[testlab]

Steve I wonder if it might help it you lift the engine up anouther hole?
Cheers

Quick question.... when you say "lift it up another hole" do you mean the trim angle on the leg or is there a height adjustment on the transon mount that raises the whole engine relative to the hull (rather than just changing the angle)?

Thanks,
Dave.

[dreemon]

Hi Dave, Yes the height adjustment holes not trim, most engines are able to move within 4 holes at the top and the bottom works with a long slot , the higher you go up the less drag you'll have with better economy and performance,

Do a search on engine height or motor height for more info, you'll know if you've gone to high when you get to much cavatation,.

I have a Permatrim on mine and used a 20mm x 20mm square tube to raise the permatrin up out of the water more when on the plane, might put a pick of it in the inventions sticky, Cheers

[steve harney]

All sounds good I only have one left hole to raise, but I was thinking that it may to too high on the highest hole I wonder!! as I said the cav plate is just getting spashed when on the plane now is there such a thing as being too high?? getting along 4-4500revs I trim out to about 3/4 & it seems to lose it's grip & doesn't go any faster. As I can tell is has no cupping at all. Does the K17 mean 17 pitch?? Deemon you said you have a k17 but you said a 13 12-d what is that a K17 size?? this is where I'm getting mixed up 17 means 17 pitch or 13 pitch, where Steve said at Solars said 13 1/4 -17 alloy one would be good with a wider plade area, as I said some people say should be revving it's tits off & some people say I should go down. When I get time I'll take down to Nudgee canel & run up & down there & see if it goes out to full revs middle load, as everytime normally I'm loaded with kid or 2 fishing gear 2 tanks of fuel going fishing out to mud for the day etc and that way I can get some real figures etc I normally just load up & go fishing, I haven't had the/a boat long & sorting as I go hench don;t know what talking about really so talking you fellows I may get to what I'm after without buy 10 props & getting the one I want
Steve But thanks for the input

[Fed]

Your K17 will be a 17" pitch Steve and with that prop it should easily get to its maximum RPM, that's why I asked about extra weight or maybe the motor not making its 90 HP.
Is the prop in good condition, no bent blades, no dings?
You have a good amount of HP for a 14'6" boat.
I think your boat should go as well as Dreemon's.
I wouldn't raise the motor either, the difference between your plate being underwater or skimming on top would only be 2 mph tops but it can come at a cost.
I believe changing your prop size to achieve the right RPM is only masking a different problem.
Carby motor? Are the butterflies opening fully, is the link & sync right?
Fuel injected motor? Are the injectors dirty, is the throttle body opening fully?
Stick with your K17 for now and try to find out why it's not revving harder.

[Fed]

Hey Dreemon, has your Websters book got the specs for a 1986 Seafarer Viking?

[Moonlighter]

Hi Steve

I've put this link up a few times previously - it tells you exactly how to tell whether your engine is at the correct height and how to tell if your prop is OK as well.

I found it to be the best information on this topic I'd seen when I was sorting out the prop on my previous boat. Just FYI, I ended up lifting my motor 1 hole so that the motor was set as per the Verado Club advice, it made a huge difference, and cost me nothing!

]http://www.veradoclub.com/smf/index.php?topic=137.0 (http://www.veradoclub.com/smf/index.php?topic=137.0)

This is the website of the Verado Club in the USA and the explanation there is from the specialist from "TheProp Gods" organisation.

Please have a read of this article before you waste time and money doing anything!

Having said that I must say that I agree with some of the earlier posts - the 146 Haines is a pretty small boat andnot particularly heavy. I used to fish out of a 146C that initially had an old Johhnno 55 and then later a Yammy 70 - and with the 70 it really boogied!

So with a 90 Yammy that's running well, you should be absolutely flying and you should get 5500rpm easily with the std 17 inch Yammy SS prop. If you're not, something is wrong, and most likely the problem is not the prop.

The standard Yammy K9 staineless prop is a pretty good bit of gear in its own right - and again, assumuing that your prop is in good nick, no dings or bends and that no-one before you has had it re-pitched, it should work well on that boat - if anything, I would have thought you could even go to a 19" pitch and still perform well.

So again, strongly recommend you read the Prop God article then go do the test as per their procedure, and see where that leads you.

Hope this helps.

Cheers

Ml

[dreemon]

It seems your prop should be ok and your engine height sounds good too ?,
how about remove the cowl and make sure the butterflies on your carbs are opening completly when the throttle is at max ( engine not running ) might need adjusting , pull the front carb cover off, at idle they should all be almost closed evenly, and horizontally level at wot. If it does need adjustment , when you take it back on the water . . . . Hang On ;D

k17 is the pitch and 13 + is diameter.

[Fed]

I agree ML, when I read the 1st line of Steve's post I thought 19" too.

[dreemon]

Hey Fed you posted similar but before me, I must type slooooow,

Your boat ( Seafarer Viking 5.5 ) in the mag says ;
Ride and performance; BTW Good lookin rig !
Like most modern day Seafarers, the viking is extremely stable, soft riding and very dry. impresive stern buoyancy or lift by the 5.5.m hull,this boat can easily handle the weight of modern, heavy 4 strokes and dfi outboards , big +.
its rated up to 150 hp and is an absolute bullet with one hanging off the back,
( what's on yours?) will still preform well with a 90hp, best power is 115hp extra long shaft, the 115 will provide acceleration and speed to spare usefull for offshore and bar crossings,


Specs;
Length; 5.5 m
Max beam; 2.3
Deadrise;19 degrees,
Hull weight; 700 kg
weight on trailer 1,350 (est)
max power; 150hp
Best power;115hp
fuel capacity;130 L

theres also a 5.2 and a 5.9, they all had a good rap, Cheers

[Fed]

I've got the old 5.2M Viking with a 1988 Evinrude V4 90HP Dreemon, would you believe the Seafarer transom plate is stamped @ 175HP, they are sure a solid boat.
It was a 70HP when I got it and WOT was 50KPH and now with the 90HP it hits 68KPH fully loaded.
http://www.comcen.com.au/%7Efed/car_boat_opt.jpg
Steve's boat should go better than mine,...70KPH?

[steve harney]

Hi All
I don't really know last time out down at Yamba fully loaded one kid a home made live well etc etc on the way back from Browns against the wind & tide gave it a boot full & I saw 65ks about 5000revs & the B/cover started trying to part company so we layed it down & everything felt easier, it jumps out of the hole real fast. we were down south on a months holiday so we were out in the boat all the time & mucked around a few times I run 2 tanks of fuel up front & long line front to back before we went down I changed the plugs cleaned the fuel tanks out, filter, I also cleaned out the oil tank & went with just Yamylube I checked cleaned out the carbs & rechecked the butterflies were opening together & close to closed on Idle, I work a fair bit & don't get much time to get out as much as I want, I have a manual on a cd here about 1000 pagers so I have to check that out, maybe it's just me getting use to the boat but I'll try & get out & try & get to wot & check the speed, when we are getting along it seems like we are flying but check the speed on the GPS we are not well it feels faster than whats on the GPS yes it's on ks not mphs, weather permitting this week-end I have a good run around and sus a few things out, if not I'll have to get a half decent mobile mechanic around & see if he can spot anything any good one's here on the Northside Morayfield way??? anyway I let you guys know what I find & moonlighter yes mate I've read that website 100 times & changed the height on the advice on the website thanks good info anyway thanks again fellows it still feels like I'm banging my head against a wall.
Steve