Prop question. Hull crack?

[taxidermist]

I have a 2002 Lowe 170, V bottom aluminum boat, 2000 year model 90HP Johnson. The motor has the stock aluminum prop 3 blade. Boat runs 43mph top end at 4500 rpm.

Would a stainless steel prop get me any additonal top end speed?

Boat is a gift from wifes Dad, has 3 hours on it on its 2nd tank of gas and I put one of the hours on it running from LeadHill to Tucker Hollow and back.

Boat sat in a dock and was beat up, the front keel has a crack.

I dont think it can be welded without taking the interior out, the crack is well above water line.

So now the question is how would a person fix this? I have thought about PC-7 epoxy.

Any thoughts on these items?

Tightlines

John

[bubbaray]

This is a subject I know a little about since I use to run the Meramec and have fixed a lot of holes. Unfortunatly epoxy is only a temporary fix. It will get you back to the trailer but with aluminum not being porous metal it doesn't hold long. In your case not knowing the history I would say it's probably a "stress" crack and not an impact crack, and aluminum will just keep going like a windshield with the twisting and turning of the boat on wakes and such. A good welder should be able to do this from the outside if he can get to it without removeing the interior as this would be a tig welder which they can control the heat very well,but there again all my problems were below the water line so maybe epoxy will work for you.

[Phil Lilley]

Would a stainless steel prop get me any additonal top end speed?

No- stainless is much heavier and will do just the opposite.

[Rusty]

As Phil stated, but with an addtional note. Prop pitch, or the degree of angle, cup on the blades will get want you want. The thing is though, it is like buying a fly rod. You have to try them out to find what works. Most boat dealers should be able to get you close to the correct pitch for what you want.

[taxidermist]

Thanks that helps, it is impact from banging the boat dock. I have a friend thats a welder so next week I will see him.

Thanks for the prop advice, that is pretty much what I was thinking, SS being heavier.

Seems the Aluminum boat should beat 43 mph, as I have a 14 (Ski King) fiberglass ski boat with a 50 Evinrude that will do almost that, using a GPS for accurate mph.

[Wayne SW/MO]

I can address the crack I believe. The hull is most likely welded under the keel, they were when I worked for Lowe and I would imagine they still are. The keel is a harder aluminum then the hull and more likely to continues cracking.

I would get the smallest drill bit I could find, carefully drill the ends of the crack, this will stop the spread, and then epoxy it. Obviously you should check every once in awhile to make sure the problem is solved, but I suspect it will.

[taxidermist]

I am going to take the boat in to the welder next week to see what he has to say about it.

Its from being loose in a stall at Beaver Creek Boat dock, sat there for over a year being beat around.

Thanks Wayne for the tip, I have done that with other things before.

[skeeter]

Taxidermist,

I have owned and run a succession of high performance bass boats since 1974 and would advise you to definitely opt for a SS prop.

Several advantages to SS being overall strength and better resistance to impacts; SS will not "deform" or bend like aluminum when coming out of the hole or turning or running wide open throttle which will yield better performance and mileage. There are many custom shops around that can do about anything with a SS prop to fit any boat, motor, owner combination. Check with local boat dealers for names of prop manufacturers and visit their websites. Several have charts where you can enter boat length, width, aluminum or fiberglass, engine horsepower etc and get their recommendations for pitch, cup, hub length etc.

[whiteriverinnmoose]

Hey There,

Ill have to agree with skeeter on this one.Not only can the pitch and cup be very customized at a prop shop, which is very important. One of the main reasons if not THE main reason a ss prop is faster is that stainless is inherently much stiffer than aluminum.The softer aluminum displaces much less water than its harder counterpart.Example:If you were canoeing down a river and tried to paddle with a soft rubber paddle and then switced to a much stiffer wood paddle you would notice a big differnce in the water displaced and your forward motion.At 4500 rotations per minute,thats a whole lot of little paddle strokes.

Good luck,

Moose

[taxidermist]

Thanks for the info. I understand the idea behind the SS.

The boat jumps out of the hole very well now. But as always we all look for a bit more.

I went to the welder and they say noway can it be welded. Most factories put a foam lining behind riveted boat Lowe is one of them. They said maybe the factory can pull the deck and remove the foam and do the work but they cannot and no other shop around Harrison will either. the foam melts and gets into the weld making the weld weaker that before.

Since the owner is a instructor of welding, I believe he is correct.

Thanks all.