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Author Topic:   prop alum/stainless? Yam 70 15 sport
trainer posted 11-12-2001 01:01 PM ET (US)   Profile for trainer   Send Email to trainer  
I am upgrading my 89 supersport from a Yam 50 to a Yam 70. I was planning to go SS, but the salesman recommends an alum prop. The reason being skinny water. Any comments? Have had SS on the 50 with no problems. Also what speed should I expect.
where2 posted 11-12-2001 01:39 PM ET (US)     Profile for where2  Send Email to where2     
Skinny water? Well, as long as you keep running in the places you've been running I guess you'll be fine. I have a SS on my 70Hp Johnson (15' Sport). The first time I strike something, I am going to wish I had a plastic prop. As long as I keep running in obstruction free water, my stainless pushes the boat to 47-50mph (13-1/4"x19" with cupping). Chine walking is a problem at that speed. I use a 13-1/4"x17" aluminum for skiing and other things that require more thrust and less top end.
Scanner Boat posted 11-13-2001 10:18 AM ET (US)     Profile for Scanner Boat  Send Email to Scanner Boat     
If you are confident that you will not hit anything then go with the stainless. Your salesman has probably seen a lot of broken lower units and is making his recomendation to be on the safe side.
TightPenny posted 11-13-2001 01:31 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
I ran a evinrude SST prop for the original 50 hp Johnson I had on my sport 15 in the Barnegat Bay. I purchased the prop in 1974. It's diameter has decreased at least 3/8" from sandbar contact over the past 27 years in the Barnegat Bay.

The prop is still in use on the 60hp on the Sport 15. The best $90.00 I ever spent on a prop. It pains me to have to replace it, but since my son weighs in a lot less than me, it tends to allow the engine to overrev.

Bigshot posted 11-13-2001 03:23 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Man now I get the nickname:) kidding aside I run only SS props. Get the SS unless you have removed blades(literally) in the past and will continue in the future. I clocked a submerged dock in my Hydra sport with a SSt on a 225. Ripped one blade off and half the other, removed the skeg and bent the propshaft but the gears were still good. Had it rebuilt anyway because insurance was paying for it but just goes to show it takes a lot more than an occasional grounding to blow a lower.
TightPenny posted 11-14-2001 03:01 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
That's where it came from. I used to bowl on a team where my father and I were on the same team. To clafify who was who, I was TP and he was TE, using middle initials to differentiate the two Toms.

A teammate christened me tight penny. It sure pained me to have to spring for a beer frame, even back when you could get a draft for 25 cents.

Oh, yeah, my father got christened tight-er. This apple never fell far from the tree.

Bigshot posted 11-15-2001 09:13 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Can't be too tight living on Barnegat Bay driving a Whaler. But then again everyone has a Whaler up there.
Flipper posted 11-17-2001 04:53 PM ET (US)     Profile for Flipper  Send Email to Flipper     
Trainer, you should install a jackplate and then your engine could run a little higher (2-3")- a TINY bit more piece of mind when running a stainless.My friend recently bought a 75 Yamaha, with a jackplate, for her Sport 15. Turning the stock aluminum prop, she still manages just under 50 mph.I think she gained one or two miles per hour with the plate. A fun rig!
trainer posted 11-18-2001 09:55 PM ET (US)     Profile for trainer  Send Email to trainer     
I got the 70 with a Stainless and am in the process of breaking it in or 'running in' as Yamaha calls it. At 4000 rpms I am running around 30 mph. The prop is a 13 - 21.

Would a jackplate eliminate some of the spray at the transom? At the present time the cavitation plate on the motor is level with the bottom of the hull.

Flipper, do you have photos of the 15 with the jackplate? thanks

Bigshot posted 11-19-2001 11:37 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Trainer the hell with a plate, just raise the engine up a couple notches. I had my 70 abiout 1/12 inches maybe 2 off the transom. You could see my power trim motor. Same on my Montauk.
Flipper posted 11-21-2001 12:03 AM ET (US)     Profile for Flipper  Send Email to Flipper     
Trainer, congrats on the new motor! With the jackplate, the only time I get spray is with the engine trimmed way in, and even then it's not huge. My cav. plate is about 3 1/2" above the transom, which is 2" higher than I could get it before I had the jackplate.It's a personal thing, but with better steering response and no-hassle height adjusting (when using different props)I found it was worth the $300 Can.To hell with it!

I'm still working on the pic's, I'll let you know - F

Bigshot posted 11-21-2001 10:02 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
sorry guys...yes you can and will benefit from the jackplate but you can also just jack up the motor. I never had a spray issue with mine. flipper is your jack manual? If you guys want manual plates, there is a guy on e-bay with new ones for $135.
Flipper posted 11-21-2001 08:10 PM ET (US)     Profile for Flipper  Send Email to Flipper     
Bigshot,I have a manual, by T.S. Marine - called the "Highjacker" (I tore the sticker off when I put the boat to bed last month).Good tip on E-bay; have you heard of hydraulic jackplates that are "smaller" ie. for mid-range engines? I would be interested in one that is not so big and overkill, like the ones used on the V-6's. I'll start another thread on this question while I'm at it... F

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