Motor Shaft Length with 20" Transom, Need Advise Please

[jtf]

Posted in another topic, wasn't sure which to use. Have until Monday to get the facts and make a decision on a good used vee 1648 Weldbilt with 20" transom. New to jets and will have one of two dealers power it up.

One swears by jack plate and the other warns against it. This is a good lightly used boat that will need re-powering, I could use some advise please.

It is a 20" transom. Does it use a 20" shaft jet. And second, can a transom be raised without a jack plate to make things fit correctly? It is not a tunnel hull.

Would appreciate some help, plan to go look Monday.

 

[jtf]

Does the transom need a riser? Need some help here please.

 

[stinkfoot]

Do you have a reason to want a jet on a V-hull? Edit:I see it is not a V hull but a Vnose. Going to measure mine. I replaced my transom as it was a couple of inches too low for my jet. Now it is in the right place and drag and spray is much reduced. Initially I did think about a jack plate and a friend made one for me. The setback made my spray problems considerably worse. My transom is 22 and 1/4 inches for a short shaft 40/30 jet on a 14 foot jon. The leading edge of the foot is level with the bottom of the boat(give or take 1/4". What sort of hp motor are you loking for? I wouldn't go less than 60/40 and preferably more if you can.

 

[JL8Jeff]

I think my Lowe is 22-24" transom but it's a jet tunnel. Regardless, I have a Mercury 60/45 short shaft (15") jet and I still have it mounted almost at the highest setting which is 2-3" above the top of the transom. My boat is in the water at the moment so I can't get any definite measurements until daylight tomorrow. But my guess would be you need a short shaft with a 20" transom. If I didn't have a tunnel (which is 2-3" tall) then the motor would be mounted down even with the top of the transom. But I see jets mounted on the jack riser plate all the time so you could run the 20" shaft with one of the riser plates. I'll try to get some real numbers tomorrow.

 

[stinkfoot]

You definitely need a short shaft and you probably also need a way to raise the motor a couple of inches optimally. The disadvantage of a 20" shaft motor is it raises your Cof G significantly.

 

[jtf]

Not finding many motor offerings with short shaft. That limits tilt/trim doesn't it? Was pricing the 50/35 Tohatsu, Yamaha 40/30. So to get the 20" shaft, it will take either transom riser or jack plate? Yes, want the mod/vee. One of the dealers said ditch the jack plate and tuck the jet close under the bottom. The least weight of motor is important because limited access launch, don't require speed, shallow++ rocky rivers. The hull weight is about 350lb.

Will call Tohatsu on Monday and check if they make a jet in 15" short shaft, assume Yamaha does too. Want to keep the foot just under the hull.

 

[mphelle]

Moving post to classified section.

 

[stinkfoot]

Yes, they do. https://www.tohatsu.com/outboards/35jet_dims.html As you can see you'll need a 22.5" transom.

 

[JL8Jeff]

I measured my transom at 22.5" right next to the tunnel. The tunnel is 2.5 - 3" and the motor is sitting 2.5" above the top of the transom. So you would need the 15" short shaft with the 20" transom or you would need a riser plate to lift it 5-6". I got lucky finding the short shaft jet motor, the boat had a prop motor on it when I got it.

 

[dhoganjr]

Need a 22" transom for a 15" shaft motor.

A 20" shaft motor needs a 27" transom.

 

[jtf]

Thanks, found out in time to make a long trip and buy a Weldbilt 1648 yesterday. It's a 20" transom. I was in a rush to get down the road yesterday to look at the boat, 2015 model. It was a long round trip but well worth it.

Called mid-morning to Tohatsu USA and a very good fellow in service helped me. They have both these jet shafts. He suggested a riser rail to get the two inches needed. The dealer who will set it up uses a small manual jack plate for this, will decide when ordering motor.

Thanks members, . The ribs are much stouter than I've seen in other mod vee Jons, wide rails, extra deck storage for fuel tank. Saved me quite a bit over a new hull, that will go towards powering.

 

[handyandy]

if you can go for a 60/40 it will perform with a load much better. Don't use a jack plate if your going to leave it as a jet. I run a jack plate but that's so I can change to a prop lower occasionally and lower the engine back down. I've been considering mounting the engine straight up and just getting second hull to put a prop motor on, but that's a ways off in the future for now I'll just stick with what I've been doing.