20" shaft on a 16" transom, low-down on jack plate?

[Dmessmer]

My boat is a 1960s 15' alum. Starcraft w/ short shaft transom. The motor is a mariner 25hp longshaft. If I was able to read the USCG rating properly it is rated to 45hp, although that sounds high?

I've read other threads on this and it sounds like the main problems are increased drag (reducing performance) and increased leverage causing more stress on the transom. But in general I would be OK with this setup.

However, I'm considering a jack plate or trying to raise the transom myself b/c I will be running this boat in low water and in the dark (hunting boat).
I am concerned that a jack plate will increase stress on the transom due to leverage effect (more than having an extra 5in" of motor in the water). And I don't want to cause this boat to start leaking due to stress at the rivets.

Can anyone comment on this concern, and/or recommend an appropriate jack plate (I see some are made for enchancing performance of fishing boats, I just want to get my motor permanently higher on the transom)

One like this? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=110292555894&_trksid=p2759.l1259

Thanks,
Dave

 

[mickjetblue]

Re: 20" shaft on a 16" transom, low-down on jack plate?

The jack plate is made to do what you are talking about, only it does extend
the motor back some, and that will exert more stress on the transom.

iboats.com store has a transom elevator that does the same lift, but keeps
the motor on top of the transom. I would prefer that to the jack.

I did a custom job on my own jon boat, and it works great. If you are into a
little wood work, here's a link to the post. It has other's input, too.
http://forums.iboats.com/showthread.php?t=269888&highlight=transom

You mentioned some concern about the transom strength. If you would post
a picture and ask for advice on that, I'm sure you'll get some good advice.


Good luck!

 

[tashasdaddy]

Re: 20" shaft on a 16" transom, low-down on jack plate?

mickjetblue, good advice.