PROP NEEDED
Printed From: CorrectCraftFan.com
Category: Buy and Sell
Forum Name: Boat Parts Wanted
Forum Discription: Parts wanted only
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=30001
Printed Date: November-17-2024 at 3:45pm
Topic: PROP NEEDED
Posted By: stang7tl
Subject: PROP NEEDED
Date Posted: May-26-2013 at 11:31pm
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I have a 74 CC 20ft southwind but the motor was changed out and it is Left Hand it has 13 x 13 LH ACME prop I think the prop is a little to big first b/c it has pretty much NO clearance like not even a 1/8th inc not sure if the spacing is closer b/c of the deep V all the way back or what? SO... I think I need a 12 or 12.5 D with a 10-11.5 pitch? Please of anyone has advice and etc please let me know also will sell this prop if anyone interested |
Replies:
Posted By: 8122pbrainard
Date Posted: May-27-2013 at 10:02pm
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Sheridan, What's the engine and what's the WOT with the 13x13. You are correct that you do not have enough clearance to the hull. It wouldn't take much time running it that way before you get a bad case of hull rash. LH!!  The PO should be shot!  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: baitkiller
Date Posted: May-27-2013 at 11:01pm
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Let me know if you want to sell the ACME. I guess Ill have to shoot myself..... but I still want your prop! ------------- Jesus was a bare-footer............. |
Posted By: stang7tl
Date Posted: May-28-2013 at 12:26am
| hull has rash already :( but can patch at family body shop. yes ill sell the prop as soon as I get another |
Posted By: TRBenj
Date Posted: May-28-2013 at 8:08am
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Something isn't right, post a picture of the prop installed. A 13" acme should have at least 3/4" hull clearance even if its sucked all the way up to the strut. If it is indeed a 13x13 Acme (431?) then yes that's way too much prop for a stock engine in that boat. Stock replacement size would be 13x12 Acme, and 13x11.5 is a popular replacement as well. ------------- |
Posted By: stang7tl
Date Posted: May-28-2013 at 12:45pm
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ill post pic later in the friday I am out of town. From what I have looked up that prop should be a 12" I would guess this is do to the deep V. what do you mean to much prop? the motor was replaced in 96 with a mer 350 EFI LH Rotation told it has 30-40 extra HP then the stock 350 |
Posted By: TRBenj
Date Posted: May-28-2013 at 2:28pm
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I have never heard of one of the larger v-hulls coming with a 12" prop from the factory. Our BFN did have pretty minimal clearance with the 13x15 it came with, though. So, if you wanted to use a conventional hand finished prop (Federal or OJ) then a 12" prop might be a consideration... though a larger, heavier boat like that would benefit from a prop with a larger diameter, in terms of performance. Comparing prop diameter vs. hull clearance between different styles of prop (like the original Federal vs. a new Acme) can be tough though, as rake will have a significant effect. Most Acme models will increase hull clearance by ~1/2" as compared to the same diameter Federal, due to the extra aft blade rake that they have. Therefore, if youre saying that a 13" Acme has next to no hull clearance, then a Federal of the same size (which would have been the original prop) would not physically fit- which makes me question what the heck is going on with your set up. Too much prop = a prop with more pitch than your engine is capable of turning efficiently. 30-40 extra hp from an engine the same size (cubic inches) as stock would not drive a prop size (pitch) change. The extra hp are going to be realized at a higher RPM, so you would run a stock sized prop but spin it a bit higher (say 4800 instead of 4400). A 13x13 Acme is too large of a prop for a 350 in a boat as large of yours. 13x12 would perform much better, and 13x11.5 probably even better than that. ------------- |
Posted By: ArtCozier
Date Posted: May-28-2013 at 2:40pm
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Are we sure that this boat has the correct shaft in it? Too short a shaft will put the prop closer to the hull..... Art ------------- "Art" |
Posted By: TRBenj
Date Posted: May-28-2013 at 2:57pm
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We shortened the shaft on our BFN by 1.5" (from 41" to 39.5") and purposely minimized clearance between the prop and (new, 6A6) strut- ending up with 3/8". We still have about 3/4" clearance to the hull with a 13" Acme. The only way the original poster could have ended up with less hull clearance than us with the same size Acme is if one of the following is true. I am operating under the assumption that the 79-80 BFN (pre- keel notch for the 14" prop) and 20' SW are pretty much the same boat from the waterline down- including powertrain/shaft/hull geometry. 1. Their shaft had been shortened further, which is possible with the original 6A strut. It could only be 1" shorter though, and even that might not be enough to leave <1/8" clearance between the prop and hull. Again, an original 13" Federal wouldnt come close to bolting up if this were the case. 2. The prop theyre basing their measurements on isnt really an Acme, or perhaps one of the few Acmes with less aft blade rake than is typical. (Im not aware of any 13x13 Acmes that fall into this category). 3. Something about their set up is really strange... combination of wrong strut (shallower angle?), wrong prop, etc. ------------- |
Posted By: stang7tl
Date Posted: May-28-2013 at 5:40pm
| The boat screams with this prop. I would really prefer a 10-11 pitch 4blade? b/c I will be running 1500-2000 ballast in it. I am new to inboards I have only had jet and I/Os and in my I/O I ran 1600 ballast with a 17p 5 blade with its 3.0 4 banger |
Posted By: stang7tl
Date Posted: June-01-2013 at 3:21pm
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ok I have looked at the prop again it is a 13 x 13 1" Super cup federal prop |
Posted By: 8122pbrainard
Date Posted: June-02-2013 at 9:34am
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Sheridan, You can NOT compare I/O props and jet impellers to inboard props. If the boat "screams" with the 13 x 13 prop, a 10 to 11 pitch would overrev the engine to the point of a major engine catastrophe plus, modern CNC 3 blades outperform the older 4 blades. Get I/O, jet and 4 blades out of your mind! I asked you for a WOT RPM and did not see an answer. This will help with us recommending the proper prop. Also, get us some pictures of the prop/strut/hull area. It sounds like that "marina" did a hack job when they repowered the boat. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: stang7tl
Date Posted: June-02-2013 at 1:30pm
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I am was just explaining what I had to do get my I/O to get on plan and hold speeds with that much weight and I just need a prop to get on plan fast and hold speeds at low end for wakesurfing. I understand the rpm can run over and would need to watch it. as far as blades I have noticed that if you go down in pitch and add a blade per pitch it will help counteract the higher rpm b/c of extra weight and surface area. When I get the boat out again I will see what the rpm set at WOT |
Posted By: 8122pbrainard
Date Posted: June-02-2013 at 2:49pm
I do not feel you theory is true. No matter how many blades you have, the pitch is the key figure for RPM's to MPH's. Granted, the old 4 blades with more surface area had less slip but that's not true anymore with the new CNC machined 3 blade props.
------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
stang7tl wrote:Posted By: 4woody
Date Posted: July-15-2013 at 11:11am
| I have a 12x12 lh that I bought turns out my boat was a lh its a nice one |