long shaft/short shaft conversion

[bennykenny]

i recently bought a 2007 6hp merc for my tinny,its a long shaft motor,but i got it for a good price, just wondering how much it would cost me to convert it to a short shaft and is it really going to be worth it, it does slow it down considerably as i have been next to other boats the same size and with the same motor, or should i just leave it as is. cheers bennykenny.

[foxx510]

Is it possible to mod the transom to lift it up a bit? That might be the cheaper option.

[bennykenny]

as im not a "handy man" i wouldnt be able to do it myself, so again would have to pay some one to do it so i could see there would be too much a difference in price for both 'operations'and it is only a tinny

[finga]

Bung a picture of the back of your boat up BK.
Some informed people might be able to offer opinions about various options and their costings.
It's only a 6 so extending the transom maybe an option or even a bolt on bracket on the transom maybe an option.

[tunaticer]

Some of the older models of evinrude and johnson had a spacer section to alter from long to short shaft. Does your motor look like the leg is in two pieces above the cav plate?

Jack.

[cormorant]

If it is one with a spacer you can remove it and either get a shorter driveshaft from a wrecker or just have the existing one cut shorter and welded in the middle.

A 5cm box alley piece or wood with a couple of ally plates acting as a transom riser is cheap and although won't get a perfect height every cm makes a difference. Bit harder on the transom but as long as transom is rated 10hp you won't have an issue.

[patrol50]

mate just raise the transom up with ply on both sides and / or a foam centre or use cedar planking centre and then dowelled and glassed into place with 2 pot epoxy if you paint it silver will almost look as per the aluminium - will work fine i know i have done it - much cheaper than shotening the motor the cost of parts and labour will be somewhere around $ 600 to 900 probably depending if new or second hand parts available
see you rob

[Noelm]

shaft conversions tend to be very expensive, mainly because of the drive shaft, it is a pricey item, cutting can be done, but it needs to be done properely, and that also cost a lot of cash, far better to see how high you can mount it without any mods, then see what can be done, there is 5" difference, but you have about half that just by raising the motor to the top of the transom (usually)

[trev1]

If its a tinny, any half decent ally fabricator should be able to weld in an extension. I done this years ago and the peice of ally and having someone weld it in only cost $100 - $120 from memory.

[Blaster Bretty]

The difference from long to short shaft is usually about 5 inch's so my advice to you if your on a budget is to raise the transom height, very easy to do, if you feel you cant do it yourself I may be able to help coz I live around the corner in bethania, about 5 mins from loganlea.
I have done this conversion on my 12 foot glass runabout, I too bought a long shaft motor without realising I only needed a shorty, thing is when you buy privately it is very hard to get your money back, very hard indeed if not at all.
I had to glass in a good 5 inch's on to the transom but in the end it was all worth it, I slammed a big 40 horse johnno in place of the cranky old 6 hp the boat came with, needless to say she gets up + go's now, no probs so far and ive done at least a dozen outings in it so far and all seems well, except the fuel bill LOL.
PM me if you want me to pop over and give you some advice or a hand, I cant see a prob with raising your transom for the same size/weight motor.
p.s cav plate must be in line with bottom of boat no matter what you do, some blokes will differ on this 20 mm or so but its a good starting point.

Bretty

[bennykenny]

thanks guys you now have got me thinking raising the transom is the best way to go, ill have another look at it and have a look around for materials and let you know how i go

[goldfish]

i have just done this change on a old straight 6 merc. i found the cheapest way was to replace the gearbox just unbolted the old one removed the spacer changed a few studs & bolted the new gearbox on. so if you can locate a cheap gearbox its a easy way to go.
cheers
rick

[finga]

i have just done this change on a old straight 6 merc. i found the cheapest way was to replace the gearbox just unbolted the old one removed the spacer changed a few studs & bolted the new gearbox on. so if you can locate a cheap gearbox its a easy way to go.
cheers
rick
The good old tower of power. Gotta love them ;D

[Noelm]

the just replace the gearbox is fine as long as your Motor does have a spacer (a lot don't) and the gearbox is complete with drive shaft and water tube plus gear linkages, other wise you have just bought a spare gearbox.

[finga]

I've been thinking about this a bit.

How would an auxiliary outboard bracket be bolted to the back??
Just like this one.
http://www.discountmarinesupplies.com/product.cgi?group=71388&product=92829

or this but make it fixed, not up and downable
http://www.discountmarinesupplies.com/product.cgi?group=71388&product=92827

or just make a little pod up for her. That'll give you more room in the tinny ;D

or bolt a bit of 8x2 hardwood about a foot long on the back and just bung the motor on top.

[bennykenny]

I've been thinking about this a bit.

How would an auxiliary outboard bracket be bolted to the back??
Just like this one.
http://www.discountmarinesupplies.com/product.cgi?group=71388&product=92829


or bolt a bit of 8x2 hardwood about a foot long on the back and just bung the motor on top.
ive been thinking alot about this myself over the last couple of days, sorry couldnt get the photos yet the missus took the camera away for the weekend, i like the look of the first bracket not to bulky looks like it bolts on easily and looks like it would give a bit of height, i was considering the piece of hardwood bolted on top, just because you could eaisly take it off if i had to, if i replace the motor again one day, might give it a go first seems the most simple option and cheapest. thanks finga, cheers brendon