1981 sea nautique transmission and rudder question

Hi guys I recently acquired my first Nautique. It’s an 81 sea Nautique with 351W power.

When buying I was focused on the structure of the boat and somewhat rushed by my pops who I brought along to help look over the antique engine haha.

We were land locked about 45 mins from the nearest water so we didn’t get to put it in the water but rolled the dice.

My questions start here:

While the engine idles in neutral the prop is spinning as if it is in gear, is this normal or an issue? It does “click” into forward and reverse and while tied up to the dock it is spinning but not creating the same thrust as when clicked into gear

The boat doesn’t respond to any rudder response when reversing which makes me believe the rudder is too small (reinforcing my original visual suspicions )
Does anyone know how big the correct rudder should be on the 23?

Are there replacement larger rudders available?

What size shaft should the prop shaft and rudder shafts be?

How do I find transmission ratio? Should I repack with dripless packing or use a pss dripless

Last question is

Does the 351 fuel system use a return line or is it possible to put a fuel sensor in line to monitor fuel burn?

There are far more knowledgeable folks than me on here when it comes to setting up fuel systems, but I have a primer bulb in my fuel line between the tank and the pump. I find it useful and doesn't cause any issues.

I’m assuming the prop shaft is 1 1/4” after measuring it with a pair of calipers

The rudder in the thread you linked looked much larger than the rudder on this boat.

I will take some pictures and play with it some more this weekend. With the primer bulb you can hear the anti siphon jiggle

The bulb is between the tank and the fuel water sep then it crosses over to the engine.



I have no idea where to start with carbs or how to even mess with it. I will try hooking up a gas can and running it from there.

How do I drain/fill the trans and what does it take? I read if they are over filled they will spin in neutral. I think I cooked the cutlass with it spinning while on the fake lake. I will have to pull the shaft and replace that.

Is the “dirty idle” an issue that needs to be fixed? I can live with it if it’s not a real issue but I plan on using the boat a lot and don’t want to end up stranded somewhere bc the transmission let loose or something

https://photos.app.goo.gl/WwQsbPXn5wJFNXRz7

This is the current rudder it seems too small does anyone have a picture of a rudder from a fish nautique or similar 23ft cc?

Yes I would love some dimensions

Thank you! I would like to have any kind of control to pivot the boat in reverse to get out of our slip

I don't know what kind of conditions and currents you get on the west coast but out here on the east coast and with the type of fishing i do(lobstering and striper mostly) i needed low speed maneuverability so the larger rudder did make a difference for me. if all you care about is going fast the 11A is probably your better bet.

So we were running her around yesterday and after new cutlass + packing and trans linkage adjustment we had a good idle without any spin but now we have 3 speeds of forward.

Forward = fwd
N= fwd
R=fwd

Facepalm looks like I’m pulling the trans and learning how to rebuild it. Any pointers?

I’ve been looking for a rebuilt one but need help there too. The belts turn to the left when looking at the engine and R hand prop rotation. Anything special with the trans or ?

Thank keno

I was able to use a sharpie trick to get the numbers of my trans

It’s a 10-17-001 is it worth rebuilding or should I pick up a cheap 003/4

Or I also found a 10-18-002 that looks real clean would it be worth picking up and going thru? It should fit just heavier duty version?

What trans cooler do I need to order to replace the one I have after I get it fixed? The one in there seems really small only 5” or so long I don’t know if it’s keeping everything cool enough under load with all the boat loaded down

Getting back to your "3 speeds of forward", may be a silly question but have you made sure it's not just a broken shift cable or cable end at the throttle control or at the transmission end?

So I pulled the trans took it in and had it rebuilt so I didn’t have to deal with any screwups on my end and I actually ended up finding a clean 2000s era trans for a good deal I ended up having done up. Got it all re assembled and ran into alignment issues well I’m not sure if they are issues but I’m trying to realign the boat since I got new mounts as the old ones were seized up.

Any tips tricks or anything? I have to try and scoot the engine over I think letting the shaft rest and lifting straight up I’m left with a larger gap on the port side than on the stb side with even gaps on the top and bottom

link