Need to know which prop is best for my new (to me) boat.

Chris' Craft

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I purchased a '95 Chris Craft Concept 20 yesterday that needs a new prop. since i have no previouse experience with this boat, i have no idea whether the current prop which is dinged, works well or not. after looking at options, im thinking i want an alluminum. this boat has the OMC 4.3L, its 20ft long and the previous owner stated it weighed in at around 2900 lbs. i will do very little skiing, wake boarding, etc, but will have 3-6 ppl on the boat at most times and will most likely pull a tube most of the time. this tells me i wont need a strong holeshot but dont want to totally lose it. im sure i will most likely cruise around 30-35 but would like to run up to 45-50 on occasion. im thinking handling will be most important to me. can you guys please help steer me in the right direction as to brand, hub needs, pitch and diameter?
 

Robbabob

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Re: Need to know which prop is best for my new (to me) boat.

Hi "Chris' Craft", welcome to the best boating forum I know of!

Sounds like you haven't had her on the water yet.... since all boats behave differently with various setups of engine/prop/gears/load(distribution), we can hardly give you input on where to start. However, this link to a sticky at the top of the page will help: http://forums.iboats.com/showthread.php?t=287818

Your best bet maybe to get your current boat wet, run some tests and post pictures of the current "dinged" prop. Your details and pictures will help us help you.

That many people and pulling a tube is similar to the set up you'd have when skiing or wake boarding; you do want a strong hole shot to get up quicker on plane.

Good luck!

btw: Need help please!!!! is not a good title to give a thread, next time, briefly state what the question or problem is.
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

haha, yeah i read the "how to" on thread titles "after" i posted, which is why i changed it (freaking newbies)... the reason i havent ran it yet is because i didnt want to damage the drive bearing or seal and end up with water in the tranny. its not a horrible ding but maybe dime size, so i just figured i would replace it first. i guess i need to make an afternoon trip today so i can get a good reference. thanks so much for the advice, ill do just that! ill give some more info as soon as i get back from the lake.
 

Robbabob

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Re: Need to know which prop is best for my new (to me) boat.

Well.. before you go, tell us what pitch is currently on it. I might assume it is Aluminum as it has a dime size ding... which probably wouldn't happen to a SS (for many reasons). Also, the term ding could have various meanings.. .to me, dime size is pretty big. That much may skew the results a bit.

Look on the outdrive and let us know the gear ratio.

Something just occurred to me... you purchased yesterday and it hasn't been on the water with you (as in a test drive/ride)? Tell me it isn't so! That, or you know and trust the previous owner.

Robb
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

no, i test drove it but just dont think i have enough experience driving this boat or any other for that matter to make these decisions without some advice. i just meant i havent had it in the water since i brought it home. im at work right now but will get you guys that info when i get home.
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

ok it has a 19 on it now and the only thing i could find on the foot that resembled a gear ratio was 1.66?
 

Robbabob

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Re: Need to know which prop is best for my new (to me) boat.

Next step is to get us the answers from the link I gave up yonder. Not sure you will be able to hit the 50 mph mark, but probably mid 40's.

Do you think the previous owner knows what the rpm was at WOT before the prop damage? REAL data is our best friend.

During your trials, make sure to keep the rpm below 4800. You can go for more at a short duration just to find what the max you're turning, but be very careful.. don't want to damage the motor :eek:
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

ok, itll be tomorrow before i can get you some of that. im going to change the oil, filter, fuel filter and gear oil in the foot and take it out for a good test tomorrow and ill get all that for you. is that "1.66" what you need or do i need to look further?
 

Robbabob

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Re: Need to know which prop is best for my new (to me) boat.

Assuming you have a Volvo SX drive, 1.66:1 is probably correct.
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

well actually ive been wondering about that. it doesnt say anything other than OMC cobra and i looked for a brand on the engine and the only thing i can find is it says Vortec on the vavle covers which i assumed was a chevy since they have the vortec engines. is there a way that i can tell for sure?
 

Robbabob

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Re: Need to know which prop is best for my new (to me) boat.

There should be a tag on the engine side (air cover) stating details for HP, rpm max range, plug gap, etc. Another tag wil have the engine model and serial number, and outdrive serial number. Use those to cross reference your manufacturer.

Perhaps you do... mine's a Ford. We're now going to have to wait on Don S (or anyone far more familiar than I), to work this through. 1995 was during the transitional years. Unless your outdrive was refurbished, I would think it still has at least an emblem on it.

Post pictures (probably in the OMC forum) asking for assistance on "what you have" for motor and outdrive. I started in the wrong direction by assuming too much, my bad.
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

no worries, i'll do just that and get back to you. thanks again for your help.
 

Chris' Craft

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Re: Need to know which prop is best for my new (to me) boat.

ok, well i took it out and put it throught its paces, and i guess all this was for nothing because there is no vibration at all. now on to other issues...
 
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