Putting a long shaft engine on a short shaft transom

[Nasher]

Originally Posted by 9D280

I do have to ask here - add one lump of oak to a couple of square metres of 6mm stainless - that's a LOT of extra weight to add. Surely a siezed short shaft engine for a leg swap would provide you with a far cheaper and lighter alternative?

I had to consider the weight when I did mine, but the XL shaft Engine I picked up really was very cheap.
And of course the extra weight was less of an impact on my 6.5M boat when I was putting a @200Kg engine on the back.
The added benefit I had was raising the powerhead up where it was swamped less often, wich is a dissadvantage of cutting a Transom down in the first place.

It comes down to a compromise of doing what you can on the budget you have, or not being able to use the boat at all.

nasher.

[9D280]

Nasher,

Agreed the weight gain on a larger boat will be proportionally less, but Pablo's hull is not dissimilar to my own (sized to fit a standard garage if my memory of earlier posts is correct!) Also vaguely remeber it's a Yaminer 60 2- stroke -therefore probably not a new engine, so likely to be a few dead ones kicking around to nick the bits off.

Well, that was my theory, which has worked nicely for 2 25Hp lumps on my transoms so far....... Admittedly I don't mind taking engines to bits

Also agree that it will reduce swamping potential, but isn't that what the trunks are for? Seriously though, my new boat has a cut down transom very similar to Pablo's, so I may end up revising that thought when I finish the rewire & get it out for a proper run......

Shame that budget is usually the ruling factor in these games

[Nasher]

Hi

The swamping I was refering to was when you shut the throttle down and the wake catches up to you, then goes over the transom.
The lower transom not only allows the powerhead to get more water over it, but also allows more water in the boat.

Of course there are many ways to do most things, and much to consider.
I'm really no expert so shouldn't really comment too much.
In my case it normally comes down to the cheapest way unfortunately.

Nasher

[9D280]

Alter course 30+ degrees to your current direction as you throttle back, the wave then passes behind you.........(also stops you getting pushed forwards as you surf your own wake) Option 2 is throttle back very, very gently. Granted you don't always have the time or space to do so!

Agreed you get more in the boat, but most engines have baffling etc to stop big waves like that getting into where it really hurts.

Yeah, and unfortunately when you mention the words "rib" or "outboard" you can normally see them grinnig like the proverbial Cheshire Cat as they hand you the cedit card reader.......

[Pablo]

I'm paying 1500€ for the motor, the transom redo and the rigging including everything. It's an old Yamaha 2/stroke, autolub, electic start, tilt & trim. I also get a one year garentee. The guy has hundreds of outboards lying around because the ones in the worst state (like my old one) he sends to Africa for spare parts. He said that it wasn't worth swapping around engine shafts.

When the original owner brought the boat from Humber they made a mistake in cutting the transom for a short shaft. He had an engine that was between the two. The guy in France had never seen that. Anyway, Humber quickly made up a plastic sheet to put on the transom to prevent swamping from following waves.

[9D280]

No need to justify it - if it works for you, then what's the problem?

I guess I was lucky in that I found a couple of dealers with a heap of old engines, and most of them were there because the dealer couldn't justify the time to repair vs the increased profit he'd get selling an ancient runner versus breaking it for spares. As an amateur who enjoys tinkering with engines I don't have those commercial pressures to keep my pay coming, so can play with the engines at leisure.

I'd be interested to hear what the difference in "swamp factor" is with your new transom - my new one has a small cut-out and when I finally get out in it I'll be interested to see how much more it takes on board compared to the old SR. Only about 9" (approx 23cm) from the waterline at rest to the cutout!

[Pablo]

Originally Posted by 9D280

I'd be interested to hear what the difference in "swamp factor" is with your new transom

I don't think i'd be able to reply as i've not yet had the boat on the water. It came with a broken engine !

[fred bolton]

Is there an insurance issue with this type of mod?

[yorfuoj]

another tool to raise the motor, without risky approximative work ...

With that, the boat handles better because the added 12cm length increases the lever arm of the motor to control the hull.

A bit more speed too, because the motor can be raised by at least one hole.

Made in marine alloy, extra weight is roughly 17 pounds. Max power is 235 HP.

[Pablo]

You came too late yorfuoj

Here's the finished job.