Interesting. I'd be curious to see if other twin engine DVs have the same bolt spacing.

I noticed that it looks like bolts have previously been in the holes above and below the current top bolt hole.

I think my single 25" engine top bolt holes are about 3/4" lower than your top bolt hole, and my engine is also mounted on its second hole. I think my engine could stand to be raised one hole, and it runs at the deepest part of the hull, so imagine how deep yours are.

If clearance allows, you should be able to fill those lower holes and redrill about 37mm higher to put them at the right spacing, but I suspect that when you move the engines to the highest position, you'll still be buried a little bit.

Check out the rigging guide for bracket hole spacing. http://gfretwell.com/ftp/Rigging%20guide%202012.pdf

Ahh, read this: https://www.thehulltruth.com/4737502-post5.html

Not to derail, but what boat please? length, weight deadrise...Appreciate the info.

Tidewater 21 bay boat. 15 degree deadrise. 2100 lb hull weight.

https://cimg7.ibsrv.net/gimg/www.the...9871c7e35d.jpg
Motors are level

https://cimg9.ibsrv.net/gimg/www.the...8c1b6a593b.jpg

From those pictures it looks like the cav plates are actually below the hull.....looking at a level, straight line. Not good. As the water comes of the transom, the white area in your case, it rises up at an angle meaning the water is going to hit well above the plates. More unnecessary metal being pushed through the water. Take a straight edge and tape it to the hull in line with your engines, see where the cav plate hits.

i think we're at the point where it doesn't matter if the engines are low or not. If the OP is willing to redrill new holes, then we can start talking again.
FWIW, they look low and I can almost guarantee that that is your speed/rpm issue.

Personally, I think it would absolutely be worth it to drill new ones and fill the old ones.

I dunno.. They don't look terribly low. An inch can make a difference, though. May pay to get a professional opinion and look at the props a little more before spending the money.
Do you have a good Yamaha shop to deal with ?

Marc

I have the same setup. I went with Enertia 19 pitch props and there was definitely a performance improvement. I did a lot of searching and there were a couple people that commented that these are the best props for this setup.

The engine mount holes definitely look weird. Looks like the top bolts are going through the cap? The top bolts on mine are just below the cap and engines mounted on lowest hole. Hope this helps.

​​​​​​https://www.thehulltruth.com/boating...-s-vs-sws.html

This should help

FYI, there is a 23DV owners group on FB if anyone here is interested.
https://www.facebook.com/groups/1308882279266673