New outboard Short or Long?

[mickjbuist]

Hey guys I am looking at purchasing a new 30hp 2-Stroke for my tinny but am unsure of the length i need.

My transom measures 430mm in the lowest point.

Should I go with say the standard model which measures 423mm or should i look at the long shaft model and maybe extend the height of my transom by say another inch or two?

The long shaft model measures 550mm.

Thanks!

[Noelm]

unless you want to do a lot of modifying, then buy the motor that suits the boat, you will need to raise the transom about 120mm= 4-5" not overly difficult (but it could be) but not necessary if the correct length is available.

[BM]

Don't forget that with a tinnie thag has an extruded keel you should have the cav plate level with the bottom of the keel so thus may give you another inch or so.

Seems as if the builder of your boat is a bit dull though. They made the transom 17 inches so it's too long fit a short shaft and too short for a long shaft without stuffing around.

Cheers

[nigelr]

Personally I'd have the transom height raised and fit the long shaft. Gets your powerhead a bit higher off the water, if nothing else. My previous boat was a 4.2 tinny with a 30 2-stroke with the longer shaft, was very happy with the set-up. Repeated the exercise with my 5.3, went the longer shaft 90 2-stroke, I love it.
Cheers.

[mickjbuist]

it does appear that someone has cut the transom down before.

If i raise the transom 2" and with my keel being another 2" then it should fit a long shaft beautifully.

Problem sorted!

thanks everyone.

[STUIE63]

have a read of this it will help with the engine height . I believe when the cav plate is parallel with the bottom of the hull then your cav plate should be about 1" above the bottom of the hull . this does vary from boat to boat though . most motors I have seen fitted I believe are set to deep . this is so that the motor never cavitates but the boat will work alot better with the cav plate just skimming the top of the water . the motor will cavitate on a hard turn but it will work better in every other way . have a read here there are some good photos as well http://www.veradoclub.com/smf/index.php?topic=137.0

[BM]

For an alloy hull with an extruded keel the best position for the engine is cav plate level with bottom of keel extrusion. For a glass boat cav plate level with bottom of boat.

This provides the best basic engine setup.

Yes, you can start raising engines and all manner of other things. Can even go to surface piercing props and low water pickups if you want to get really carried away.

But for good all round performance, the above is the way to go.