A hydro motor height

[Skoontz]

Gotta Q for those who know more. The boat we have is a Lovecraft, and the bottom has 5 steps from the middle to the end at the transom. So, that means, for every sheet of wood on the bottom, essentially, it raises 1/4". So, when I take a motor depth guage at 1.375 and line it up, do I simply use the last lift of wood, which is a sheet about 1'6" long, or am I required to lay the guage across the high spots of the steps through that entire 4' of bottom and use that as the basis for setting the prop shaft?

If that's what I do I need to raise the transom an inch so I can get the right motor height and still have enough meat for the turn buckles to clamp on to.

When we ran J at Parker, we were about 1/2 to 3.4" lower than we really should have been, but, that helped plane the boat off, as this boat is hard to get off plane to begin with...

Also, what brand of epoxy do I need to use to bond with the wood? And where do I get it?

Thanks in advance for any advice.

[ryan_4z]

You measure off of the flat surface. Most of us use West System epoxy. You should be able to find it a local West Marine or similar marine supply store.

[ZUL8TR]

The depth to the prop shaft centerline is 1-3/8" and >>

must include all steps within 48" from the end of the prop shaft according to the stock outboard tech manual on the APBA site. So in your case determine which step is within the 48" and use it as a flat durface to measure the prop shaft depth below the bottom. See the rule book if still needing additional information where they have a picture.

[Andrew 4CE]

I haven't read the rules in a while... but I thought the bottom must be flat with in 1/16" for the last 18" of planing surface?

I thought steps/tunnels/etc were illegal in J/A classes?

Edit: sorry reread... your step does start at 1'-6" forward or 18".... therefor I believe you would just measure off of your last piece of wood as you say. The checker is only required to measure the last 18" of planing surface is my understanding.

I've never heard of a 48" rule? I better do some reading I guess.

[ryan_4z]

Andrew is correct, the back 18" of an ASH must be flat between the airtraps with a 1/16" tolerance. Foreward of 18", steps are legal. The inspection tool for measuring height in ASH does not go forward 48". In ASH the height is measured off of the aft end. If you set up as per the diagram for step bottom boats in the inspection manual, you will probably be running too high, and be disqualified. ASH height has always been measured off of the rear 18" planing surface.

[ZUL8TR]

Prop shaft height

Take a look at pg 6 in the SO inspection manual at following link:

http://www.apba-racing.com/Forms/200...h%20Manual.pdf

Copied from the link above see page 6 in manual for the pictures and note the very bottom picture for measuring hulls with steps (need to go to link for the pictures).

Note that the depth to the prop shaft centerline is from the flat planing surface defined in #4 below as the lowest wetted surface at the aft of the boat forward excluding air traps. I do not see anything about measuring the last 18" of the planing surface as noted in other posts but the pictures do show a 48" distance measured from the aft end of the porp shaft forward that appears to be the measuring zone. However note #7 and 8 below as a wiggle place for the inspection procedure du jure. Perhaps after viewing the pictures a clearer explaination of the rule can be posted.

Hydroplane Height Restrictions

1. For safety reasons, all Hydroplanes competing in the Stock
Outboard Category have limitations on where the engine may
be mounted on the boat transom relative to the bottom of the
boat.
2. Hydroplane heights: ASH =1-3/8”: BSH, 25SSH and DSH =
0.0 CSH and 20SSH = 1/2” SO Classic = 3/4” The center of
the propeller shaft at its aft end must be at or more than the
above dimensions below the planing surface of the boat .
3. For ASH only (new 2006) – Two measurements are
required. The aft end at the center of the prop shaft and
the forward end at the split line of the gearcase. The
maximum allowable height difference between these two
measurements is 1/2'”.
4. The planing surface is defined as the lowest wetted surface of
the hull at the aft end of the boat forward excluding airtraps.
5. The exclusion of airtraps shall only be allowed so long as the
airtraps are not greater then 5/8 inches in depth at the aft end of
the boat and 1-5/8 inches in depth at the point 18 inches
forward and, in addition, are not any wider (ie: thickness which
is measured transversely) than 7/8 inches each.
6. The previous definition of “airtrap” in number 4 above, shall not
be construed to include any wetted surface which obviously
does not serve the purpose of trapping air.
7. The following diagrams are intended as a guide for the
measurement of the restriction described above.
8. Consequently, the procedures and/or tools used by the
Inspector to measure this height restriction shall be deemed the
procedures and/or tools for the day.

[Haüenstein]

definition of planing surface

You want to look in the SO/etc. Rule Book rather than the SO Inspection Manual.

Check Rule 20, pp. 29-33.


-Mike

[Norm Schaub]

See rule 4-C-3 on Page 33 in 2007 Rule Book.

[ZUL8TR]

The SO rule book on the APBA site only has 27 pages but it contains a Rule 20and it describes the ASH motor height on page 20 under C 3). So which rule book has pages up to 33?

[ryan_4z]

In the rule book, the Outboard Racing Rules section is 43 pages long. On page 31, as Mike said, there are rules on Stock Outboard hulls. Under the section on hydroplanes it reads--"ASH motor height shall be measured relative to the lowest planing surface at the aft end of the boat." Since the rule on ASHs only deals with the aft 18", that is where the height is measured from.

[Haüenstein]

same rule

The SO rule book on the APBA site only has 27 pages but it contains a Rule 20and it describes the ASH motor height on page 20 under C 3). So which rule book has pages up to 33?

The downloadable rule book and the green 2007 rule book we all got in the mail from APBA have different pagination, presumably so the PDF won't be so long when printed on 8-1/2 x 11 paper. I think most people refer to page numbers in the rule book printed by APBA because it's more convenient to carry in the pits.

Regardless of page number, that is the rule for which you're looking.

[csh2z]

Maybe our S.O. Rules committee can look into clarifying issues such as these.

[Haüenstein]

Maybe our S.O. Rules committee can look into clarifying issues such as these.

Is there a subcommittee for this?

[hydroplay]

How can the SORC rules committee straighten thing out when they are the very guys who got it screwed up to begin with?

[Skoontz]

Thanks for the sort of clarification. I think, along with trying to decifer the rule book, I'm going to get a hold of Roger Carr to see what he says as well.

As it stands, the motor rides about 1/2" lower than it should, and that is shimmed as high as I can go and still have enough meat on the transom for the clamps to bite. So, before I raise the transom, I'll seek the ones who can steer me best.