Adapt, improvise, overcome.

[JamesG161]

If you use any glue rated for laminate gluing, your stress will be distributed along the wood laminates. Notice the alternate colored laminates. That is a high stress design.

Here is how mariners have sealed their woods for many years.

https://en.wikipedia.org/wiki/Spar_varnish

About 3 coats of SPAR VARNISH, with 120 grits sanding between the coats will seal wood/glues from marine environment and provide the most beautiful finish to show off your tiller.

Jim...

PS:Additional support at the rudder tiller junction as mentioned by others would be good. Just remember to "spread the stress" (like washers do) if you can.

 

[Daveinet]

I don't think Titebond glue is rated for marine use. I know they have some new formulations but epoxy would be the choice for a tiller handle that gets constant exposure, and provides critical function. Even resourcinol would be preferred, but the bond is less elastic than the better epoxies.

Titebond III is waterproof. Even so, the tiller is not going under water for days at a time. Also of note, only the edge would be exposed, so the glue would not get wet anyway (assuming it was clamped properly). If the glue was getting wet, that would mean the wood would be completely saturated with water. At that point, it would not be the glue one would worry about.

Or one could just dip it in the ocean for a few days. The ocean life would glue it for you

 

[Roadking Larry]

I glued it up with Gorilla Glue, and I'll add a couple of through-bolts backed with washers. I'm pretty sure it isn't gonna come apart along that glue line anyway. I completely stripped the old finish and will recoat with Helmsman Spar Urethane as many coats as it takes to get the finish I want.
I'll post another pic when I get done with it.

 

[marke14]

That'll buff right out.

 

[Roadking Larry]

You crack me up.

 

[philwsailz]

When I repair split tillers I will usually go to the table saw and cut about 1/4" of material away both sides at the end near where the tiller bolts in. I will then glue on some patch pieces to either side of the tiller. The idea is to provide a "web" of wood that spans the split, and also spans all of the laminates. I find this will greatly strengthen the tiller at this point.

To go totally overboard, I have on occasion gone a step further and cross-drilled the newly-sandwiched tiller at the bolt locations. I will drill these holes over-sized, and then glue in dowels. After the glue dries, center-drill the dowels for the bolts.

See pics