Waterline help from Oday 23 owners

[CatBoat59]

Hello All,
New member, first post ... I'm renovating a 1978 Oday 23, and am ready to attach the new larger outboard mounting block. To correctly place it so that the motor's cavitation plate will be the recommended 2 inches under water when lowered, I'll need to know the actual location of the waterline along the hull. The original "staining" residue along the waterline that would have given me this info was removed when I cleaned, sanded and resealed and repainted the hull. (Wish I had thought ahead on that.)

So here's my question: On an Oday 23-2, (circa 1978) how many inches is it from the top of the transom at the centerline down to the surface of the water? With that measurement, I can work out the mounting block and motor mount location.

In case you're wondering, I do know the location of the original smaller mounting block (and have the block itself), but I do not know what motor mount, engine size or shaft-length the PO had. I'm planning to use a Tohatsu 9.8 - probably the 25 inch shaft depending on how the measurements work out.

Thanks in advance for any help!

 

[LeeandRick]

The surface of the water with no one in the cockpit is right at the bottom of the transom on our '78. It may not touch the vertical face without some weight in the boat. I changed my motor mount out last year. The Tohatsu 6 Sailpro pushes the boat even in a 35 knot headwind. I'll get a picture in a little while.

 

[LeeandRick]

All measurements are from the transoms lowest point (which is the waterline) on the center line of the boat. Our engine is a Tohatsu SailPro extra long shaft (25"). The bottom of our Garelick 71094 engine mount bracket is 7" from the WL. We use the 3rd lowest position normally which puts the top of the mounting board 23" above WL and cavitation plate 4" under water. In 2' chop this is not deep enough and we use the deepest position. The top of the mounting board is 32" above WL in full up position allowing the motor to clear the water, and handle of mount, on a 15° heel in the first tilt lock position. The engine can be tilted parallel to the water but you have to turn the engine 90° to clear.
We have 2x2 Aluminum inside and out along most of the face of the transom because we trailer with the engine on. There is also a support post down to the trailer for travel. Make sure you use the starboard side of the transom because the other side is not reinforced. The centerline of the mount is 15" to the right of the rudder centerline and this allows the rudder full movement without hitting the engine with our configuration. Hope this helps PM me if you need more info. This O'Day 23 is our favorite boat of the 20 (14' to 36') boats we have owned
.

 

[Sunbird22358]

That recommendation to have the anti-ventilation plate (aka: cavitation plate) 2" below the waterline is many for planning powerboats, on a sailboat I would set the motor height lower to allow the prop more chance to stay in the water in a sea. On my DS II I have the anti-ventilation plate about 7-8" (maybe lower) below the static (floating on the mooring, no one aboard) waterline.
You want the powerhead of the outboard high enough to not get dunked In a wave, but keep the prop as deep as possible (within reason), hence the reason for using a 25" shaft (or 20" on my boat). Keeping the powerhead at or near the level above the waterline where it would be on a powerboat (a bit higher is usually better) is needed to reduce backpressure on the exhaust that would be caused by mounting the motor too low, again, another reason for the 20" or 25" shaft. Rough figure (using a 25" shaft), have the top of the mounting board 17-20" above the loaded waterline.

 

[CatBoat59]

Many thanks to both of you - LeeandRick & Sunbird! I greatly appreciate the feedback, advice, experience, photos - and the time you took to respond and help me out. As you can tell from my question - I'm still learning as I go, and I'm enjoying the journey (most of the time!).

LE - based on your comment about your Tohatsu SailPro and the number of very favorable reviews I've now seen on it - I'm likely to go with that for my outboard. I love the idea of saving $ and not having the 50+ lbs of extra weight on the stern!

Thanks again to you both for your helpful and positive responses.

 

[glaufman]

Make sure you use the starboard side of the transom because the other side is not reinforced..

Is this true of all years of 23-2's?

I recently purchased a 1984 (supposedly, not sure how I can be sure) and have been thinking about switching out what looks like an original motor mount for a Garelick model, but the original is mounted on port... This might not be too surprising, as I keep finding things that tell me the PO may have cared a lot but not known a lot..

 

[LeeandRick]

The Vin number will tell you the month and year of manufacture. ( http://www.boatsafe.com/nauticalknowhow/hin.htm )

If you look at the inside of the transom you can see where the reinforcement for the engine mount bracket is. My '78 has a 1/2 - 5/8 plywood from 4" port of the rudder gudgeon to the starboard side glassed in. You can definitely see a ridge. They could have reinforced the entire transom in other years.

 

[glaufman]

Thanks a bunch ... I'll take a closer look at the weekend to see if there's something glassed in, in addition to the piece I can see (no glass) that the bolts go through...
On the HIN... also thanks, but here's a followup question I'm sure there's a simple answer to... last 4 digits of my HIN are M84D... so that would indicate December, 1984? Except being after August '84 there was a new format?
(sorry if I crossed the line into hijack)

 

[LeeandRick]

On the HIN... also thanks, but here's a followup question I'm sure there's a simple answer to... last 4 digits of my HIN are M84D... so that would indicate December, 1984? Except being after August '84 there was a new format?
(sorry if I crossed the line into hijack)

The hull of the boat was probably built before the new rules took affect with a planned shipping date of November for the completed boat.

 

[glaufman]

Just as I predicted, perfectly simple explanation

 

[Sunbird22358]

Thanks a bunch ...
On the HIN... also thanks, but here's a followup question I'm sure there's a simple answer to... last 4 digits of my HIN are M84D... so that would indicate December, 1984? Except being after August '84 there was a new format?
(sorry if I crossed the line into hijack)

Using the Model year Format like you have, The letter code in the HIN for month built is as follows: Model Year ran August to July. So, 1984 Model year was thus August 1983 to July 1984. The code is A = August, B = September, etc to L = July.
So, if your HIN ends in "D", that means your boat is a 1984 Model, built in November 1983, hence the "pre-1984" HIN Format.

 

[glaufman]

That seems to follow the research I've been doing... thanks sunbird!