Boat prop repair?

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Hi!Just wandering if anyone played with aluminum boat props, I have few busted ones and want to try to fix/weld or buildup damages myself, but can't find any info.I had them fixed in the shop before, but after spending more than 1/2 price of the new ones, they keep breaking off on the same spot.  Thanx!
Reply:Are boat props hardened in any way?  I dont know much about them, but it may be that either the wrong filler is being used or that the weld contains some cracking that you cant readily see.  Aluminum tends to be weaker at welds, unlike most steel.  Is balancing an issue for props?  It might also be that the prop is not properly balanced after welding and is slinging itself apart.  Just some thoughts.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Boat props are generally pretty soft and forgiving. Mine are usually tuned pretty good when I get them back. They fix the torn up blade and touch up other major dings in the process all for $35 to $45 bucks. New ones of the same size run about $140 to $170-ish. If they aren't balanced or the twist ins't just right you're gonna pay for it in the bottom end seal.  I have a notion it's pretty specialized work made to look easy by old pro's who have been doing it so long the tricks are automatic motions.
Reply:Back when I had a boat instead of kids, I damaged a prop - threw half a blade.It was some sort of alloy. Looked like brass.I took it to a local shop to get it fixed because the guys who specialised in doing props were too expensive.It looked fine - nice and shiny - when I picked it up, but when I put the boat back in the water and turned over the engine there was a dreadful vibration through the driveshaft. So the boat came back out of the water and the prop went off to the guys I should have taken it to in the first place.A costly exercise, given it wasn't cheap to get a 70 year old, 38' timber boat out of the water a couple of times.Scott
Reply:Looks like I may have to change the shop, I do remember vibration (have outbouard), and just found some fluid dripping off the lower. I think it is balancing issue.
Reply:I agree with Scott about it being made look eazy by old pros.Your sqaure in the middle of a probable 2 things. 1. unless the prop is a veeeery high dollar unit it is more then likely cast which can create problems for a welder that is used to just welding good qaulity billet or sheet as well as the possibilities of some wierd metal compositions.2. the main heat effected zone from the weld is probably considerably harder then the rest of the prop i.e harder equals more brittle so it automaticaly becomes a target zone for both fatigue and or impact related cracksif unable to find a shop that can show ya some examples of prop work,ask a few questions.does the welder in question plan on quenching his project as he goes or will he allow it to slowly cool down....does he do a good preheat of entire section or does he just do a cold weld.both quenching and cold welds will cause ya problems on something that is going to be seeing any kinda rpm or impactsanother solution is to talk to someone and see if they r willing to normalize the prop after welding and finishing. get the whole peice up to a good temp and let cool down under a nice draft free room temp enviroment
Reply:P.SIf unable to find a boat freindly welder u may wanna start at a good qaulity automotive place that does aluminum head repair(they should be used to dealing with contamination in cast materials)Make sure to ask em if they can normalize it after welding.....if they dont know what that means...find another shop unless theyre willing to eat the cost of the repair if it goes bad.
Reply:hey ukie, i repair props  and yes the first weld on the blade is the weakest but i have had some reapired over an over just depends on how bad the brake  we can repair up to half a blade. and balance is very important in both pitch and weight. but with prices going up ever yr its worth the repair cost. on average a new prop bout $130 an up  $300+ stainless. as to preheating i don t and let them cool in open air or a fan from back of welder. but you need to take care and not heat up too much and burn the rubber hub in the middle.but have had props that bend even at weld so they are tuff .as to ease its not hard to weld just takes practice and tig works best with use of a foot pedal.           hope this helps