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fogducker III
10-16-2008, 09:55 AM
So I am in need of some advice on prop selection. 18C with the 377 Scorpion. At present I am running a Quicksilver 21p that was reworked to 20p for some reason...? The motor spins the prop at approx 4800rpm at wot................I am around 70........I am installing the GPS as we speak.

The leg is a Bravo 1 with 1:32 gearing, ideas on what I should try? Thanks.

BigGrizzly
10-16-2008, 10:13 AM
That gear ratio would not have been my choice for that application. This is for prop selection a fact that to a point a bigger pitch turned slower is faster and that has been proven many times. The prop was reworked because the boat couldn't turn a bigger pitch. The best selections of props is in the 22 pitch and up. The quick silver is a very old design. The safest bet is a turbo1. I have other options available but don't want to get into another my prop is better then your prop discussion. My stand on props and labbing is well known on this board. If that one MPH is worth the $600 to $1000 then go for it. In most cases the correct prop runs the same as a highly modified one in mowst conditions.

fogducker III
10-16-2008, 10:21 AM
I am kinda stuck with the 1:32, came with the boat......so around a 22p? Turbo 3 blade would be your advice? Just out of curiousity, why would they have married a Bravo 1 1:32 with that engine? I was told a reputable shop installed the engine and leg together....?

I should double check on the gearing, how can I be 100% sure what the ratio is? Thanks for the info.

BigGrizzly
10-16-2008, 10:27 AM
The truth is that probably is what they had and had a bright idea because they though the Scorpion was better then it is. Actually I was thinking of a 20 or 21, I don't think a 22 could be run at 4800 rpms or better. I normally have them in stock but am waiting for DW to return them. At this time he is really busy with the ranch , business, and a soon to be Dad thing.

Donziweasel
10-16-2008, 10:32 AM
Your not stuck. Any boat service center can change the gears. I would recommend a 1.47.

fogducker III
10-16-2008, 10:43 AM
Thanks for the input, so how do I confirm what gears are in the Bravo? If the gears need changing, rough ballpark price and should I do it? Will it make that much of a difference?

If I go to a 20 or 21 Turbo, 3 or 4 blade?

Donziweasel
10-16-2008, 10:46 AM
Ooops, didn't realize you had a Bravo. I would recommend 1.50. 1.32 is too high a gear. That boat and engine should be turning at least a 22 pitch if not more.

Trueser
10-16-2008, 11:40 AM
I would check with ROADTRIP he had the same boat. Factory set up!

TRIP you on new boat vacation or what?

osur866
10-16-2008, 12:19 PM
I'd say 1.5 gears in the upper with a 25p would be a good starting point. Steve

roadtrip se
10-16-2008, 12:19 PM
Coming out of a poltically induced stupor... can't take any more.. tuning out from the rhetoric.. just finished shooting the TVs.. man that was expensive.

Okay then...

Yes, we had a Scorp 18 with XZ Bravo with 1.5 ratio. Came with a labbed Merc Mirage+ 25 three blade. Ran pretty good with this setup. Saw 75mph on occassion, but this was not for the light-hearted or uninititiated, so take your time getting there. Tried a Hydro q4 25 four blade which was too much blade.

I would not put a Turbo on the boat, because they are not a hardened prop, and you could throw a blade which will make that little wash over the deck seem like a cake walk in comparison. I would try a Precision TXP three blade, maybe in a 24,as it is a hardened prop. This is my opinion and my opinion only, please don't jump on the opinion holder as I am entitled to this opinion and will stand by it. Man I hate even breathing about props on this forum any more.

As for the ratio, I would go up to a 1.5 or even a 1.65, if you have to swap it out. It has been proven that an 18 will run better with these ratios, period.

Back to my political coma.... what a nightmare.

kramsay1234
10-16-2008, 12:27 PM
You won't need to check further than the proof that you can't spin a 21 or 20 pitch prop over 4800 rpms. You definitely do not have a 1.50 ratio, although its too bad. Thats what would work best for you. You would be better to spend the money changing the drive gear ratio than fiddling with a prop on a drive that is not ideal. You are not too far off your best speed you will see with the current drive setup if you are turning a 3 blade prop at 4800rpms. Thats just my 2 cents...:drive:

fogducker III
10-16-2008, 12:28 PM
All excellent info, so HOW do I tell what gears are in there!!:confused:

MOP
10-16-2008, 12:46 PM
You will have a little better performance switching to 1:50 and maybe a 23" wheel, a slower turning prop does better all the way around. If you stay with the current ratio I would borrow a 20 and a 19 to see if you can get the RPM to hit 5,000, IMO 4,800 is a little short on a Scorpion. No matter which way you go it always seems to take awhile to get dialed in.

Phil

BigGrizzly
10-16-2008, 01:06 PM
First of the turbo1 is hardened, all are, I have seen them made. The IF this is a real Scorpion then a 24 would be too small and a 25 would be my choice.

RedDog
10-16-2008, 01:33 PM
All excellent info, so HOW do I tell what gears are in there!!:confused:

Assuming the gears haven't been changed, and it is likely that the original gears are still installed...

my Bravo 1 has the gear ratio indicated on the serial number sticker.

I think available gear ratios for the Bravo I are: 1.5/1.36/1.65:1

Sounds like you have the 1.36:1

fogducker III
10-16-2008, 01:47 PM
So somewhere on the serial number plate/sticker should be the numbers 1:36 or similar? Thanks.

I will have a look tonight. Priced out a 1:50 gear set, around $1100 :frown:

chappy
10-16-2008, 02:10 PM
Aw hell, throw a shorty on there while you're at it, that'll really separate you from the pack.

roadtrip se
10-16-2008, 03:51 PM
Aw hell, throw a shorty on there while you're at it, that'll really separate you from the pack.

I've got one you could have cheap. Just went to all new on the SE. PM me if interested.

BTW, that gear change will make all the difference on how the boat runs out.
The boat needs a little pitch, whatever brand you chose...

fogducker III
10-16-2008, 04:28 PM
Ya, found the gear ratio stamp 1:36 :(

So now the hunt starts for the right gears, what is the advantage between 1:50 and 1:65 and should I go 1:65?

Also what is the advantage of a short leg? I realize slightly less leg in the water but is that all?

Lenny, know anybody local who will swap the gears out? Donny?

( Christ, I shouldn't have outbid Donziweasel!!!:rolleyes: )

fogducker III
10-16-2008, 04:41 PM
Would this work with my present set-up ie. gimbal etc? I guess I would have to go all the way and put a shorty on right...?

http://cgi.ebay.ca/MERCURY-MERCRUISER-BRAVO-UPPER-GEAR-DRIVE-MARINE-LQQK_W0QQitemZ310092144278QQihZ021QQcategoryZ12410 4QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Lenny
10-16-2008, 04:41 PM
Lenny, know anybody local who will swap the gears out?

Milton at Mercury marine on Dallas road can do that for you. He has also worked on Mike Millers Blackhawk without problems. I have a friend who can also do this by the name of Keith. he does all my work (motorwise)

Go with the 1:50's. Better still, and I mean better still, see what Todd (Roadtrip) wants for his Imco 2" shortie he has offered you. It has the larger diameter vertical shaft, good stuff and a slippery lower. It would be a bolt on.

I have a TXP (new) 23 you could try. I can only spin it to 4600 so I am thinking you would see 4800+. (as mine is as of TODAY :D ) It hooks up incredibly well and blowing out in a HARD turn is impossible.

Call Milton at 250-385-1457 (Mercury Marine) owner, tell him "Lenny" with the DONZI's sent you.)

fogducker III
10-16-2008, 04:53 PM
Thanks man I will contact him, so an Imco leg with the 1:50 gears should do me eh?

Lenny
10-16-2008, 05:19 PM
Here is a picture of it (business end) taken when we were in Texas fist fighting bugs... Fall of 2002

http://www.donzi.net/forums/showthread.php?t=1072&highlight=steering

http://www.donzi.net/photos/tsomerville34.jpg

Donziweasel
10-16-2008, 07:30 PM
Jeremy, the higher the gear ratio, the more rpm's you will see. A gear change is worth between 200-400 rpm's. If you are turning 4800 on 1.36, you would turn 5000-5200 with a 1.50. More torque in the drive, easier to plane, etc..... 1.65 are usually reserved for high altitude applications or HEAVY boats, which your is niether.

What I can not understand is how you got that setup. The boat originally came with a stock 350 mag with 260-300 hp. 1.36 is WAY to high for that original setup. The Scorpion was added and was not a OEM engine for that particular boat. I guess the owner felt 77 more hp would turn that gear set, but I think he over estimated the performance gains.

Lenny
10-16-2008, 07:44 PM
So, what do you think of this idea. After talking to you tonight I went "shopping" (your money, not mine :D ) What if you try and sell your Bravo 1:36 upper online (or on this site or similar) for a blow out price (quick mover) and buy this ? http://www.offshoreonlyclassifieds.com/new_mercruiser_bravo_upper-o13130-en.html

Probably end up at the same money but a new upper?

Yes, your's is a 1:36. The 1:50 will make you very happy and you will have a WORLD of props to try. Later, once you're happy, think about the shortie or whatever. But, as you said tonight, if you can get a "controlable 75 GPS" out of it at times that is plenty.

Well, you will be there already with this :)

Lenny 250-474-4005

mrfixxall
10-16-2008, 08:04 PM
Ya, found the gear ratio stamp 1:36 :(

So now the hunt starts for the right gears, what is the advantage between 1:50 and 1:65 and should I go 1:65?

Also what is the advantage of a short leg? I realize slightly less leg in the water but is that all?

Lenny, know anybody local who will swap the gears out? Donny?

( Christ, I shouldn't have outbid Donziweasel!!!:rolleyes: )


I would pull the drive off and sell it, then but a 1.65 ratio bravo and install it..
would be cheeper in the long run:yes:

A 1.65 will make the boat alot quicker and accelerate alot harder and you will also be able to spin a bigger prop..

Lenny
10-16-2008, 08:14 PM
The 1:50 will give him access to a LOT or props from everyone here is my thinking. 23-25. He will want a LOT of bow lift here, as he already knows.

I would keep it simple, and just do what is the usual. 1:65's and Scorpions in 18 foot boats isn't all that common, nor is 1:65 in any of these MERC boats.

Am I wrong?

I just want him to smile ear to ear, be able to go to the corner store and grab a prop and have a blast. This isn't high perf land, everything will be bought online and shipped. No "prop testing" here. Just $300-$500 out the door everytime you get an itch.

Ask me how I know. I have 9 to put on a wall :rolleyes:

roadtrip se
10-16-2008, 08:41 PM
MP, I recomended you as a source for parts to Fogducker via PM.

Rigger advice or not, the boat is going to respond better to more pitch which isn't going to happen with a 1:36 gear set.

After the gear switch and turning some bigger props, THEN we can talk about the shortie set-up.

The boat should turn 73-75 with a 25 pitch Mirage and a 1:50 gear set.

As for swapping drives, an XZ or XR upper complete with gears is going to be $3500 to $4000, so the gear switch would be my first choice.

fogducker III
10-16-2008, 08:50 PM
Thanks Scott, I appreciate the offer. Unfortunatly I am not in contact with the original install shop so as to why is anybody's guess...??

I will definatly send you the drive serial number and get a set of 1:50 gears from you.

Take care. Jeremy.


Have you talked to the rigger to see what his train of thought was on the gearing? I think I'd have some talk with him before I jumped up an spent some more coin on it..

If you do decide to change the gearing, PM me the drive S/N, I'll see what I can do for you on a set of gears if you want...

fogducker III
10-16-2008, 08:56 PM
From what I understand, the boat came with a 350 and Alpha leg, the owner swapped it out via a relative or close friend who worked for Merc. The Scorpion and Bravo were added together to the boat in 2000. Perhaps, as said here before, it was what they had kicking around for a leg? Either way, I will put 1:50 gears in and try it out and then see if I need to go shorty? Or if everything works within budget, I will swap gears, grab the very decent offer of a shorty and go nuts on a good prop...........? I will have to remember to save some $$ for an extra box of Depends..........



Jeremy, the higher the gear ratio, the more rpm's you will see. A gear change is worth between 200-400 rpm's. If you are turning 4800 on 1.36, you would turn 5000-5200 with a 1.50. More torque in the drive, easier to plane, etc..... 1.65 are usually reserved for high altitude applications or HEAVY boats, which your is niether.

What I can not understand is how you got that setup. The boat originally came with a stock 350 mag with 260-300 hp. 1.36 is WAY to high for that original setup. The Scorpion was added and was not a OEM engine for that particular boat. I guess the owner felt 77 more hp would turn that gear set, but I think he over estimated the performance gains.

fogducker III
10-16-2008, 09:03 PM
Did nobody see this that I posted earlier? I thought it would at least get one comment?

Straight swap for my Bravo 1 top end 1:36 and then the shorty??

http://cgi.ebay.ca/MERCURY-MERCRUISE...QQcmdZViewItem


I know, I know, WAY overkill.............

fogducker III
10-16-2008, 09:18 PM
Holy Crap! are you serious? You can not open that link?


(Mental note to self, move further into the woods)




We can't see Canadian ebay auctions south of the border. It's and Al Gore's internet thing.. :nilly: :nilly:

Lenny
10-16-2008, 09:18 PM
We can't see Canadian ebay auctions south of the border. It's and Al Gore's internet thing.. :nilly: :nilly:

Can't see 'em here either Poodle apparently.

Maybe it is a typo on your part 'cuz there is a grammar mistake already. :D

Actually, the link is incomplete I think. There is more after the end that didn't make it.



I think he should do this and sell his upper.

http://www.offshoreonlyclassifieds.com/new_mercruiser_bravo_upper-o13130-en.html

fogducker III
10-16-2008, 09:21 PM
http://cgi.ebay.ca/MERCURY-MERCRUISER-BRAVO-UPPER-GEAR-DRIVE-MARINE-LQQK_W0QQitemZ310092144278QQihZ021QQcategoryZ12410 4QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

try this.............? The guy is in Texas so not a Canadian thing!? lmao

fogducker III
10-16-2008, 09:36 PM
That Homeland Security you have is awesome!:cool:

I think that particular set-up is over kill?

The serial numbers I have are:

Transom - OL 841982

Lower - OL 746763 - Gears - 1:36R

there appears to be no numbers on the leg...?

Lenny
10-16-2008, 09:48 PM
Any grammar mistakes in my typing are a direct result of bo's internet police trying to keep the man down. I've noticed ever since he started his campaign, my keyboard has a mind of it's own..

He talks "tough" but... Let me tell you a story.

I was in New York. I was having a hell of a time trying to keep my 1.5 GPA up cuz I had to attend rehab every day and missed a lot of classes. This also made it tough to hold down a job and well, I was broke. Well, one night, late at a Motel, Poodle comes up to me and says, "you want a Beer?" I couldn't believe it. He said he had taken some risks but they paid off and he wanted to share his good fortune with someone less fortunate. I obliged, it was good, it was free and we both felt better.

Deep down, he is a Far Left leaning Liberal, don't let him kid you. ( It wouldn't surprise me if he actually just "gives" you a gearset ) The Barrack Obama attacks are just slang, and a cover so others here will think he is "tough."

;) ;) ;)

:D

fogducker III
10-16-2008, 09:52 PM
rotflmao................:canada: