232 W/ BRACKETED SINGLE: What engine height do you use??

[NIGHTIDES]

Trying to help a buddy mount his single engine at the correct height on his 232 Gill bracket.

I have seen engines mounted using the very top engine hole and also ones on the very bottom engine hole. You would think that there would be some uniformity in how high/low the engine would be mounted. Perhaps the Prop used is the reason for the variation..

Anyway.. where do you have yours mounted and what type of WOT and fuel burn are you achieving..?? Thanks.

 

[VeroWing]

As a "rule of thumb", outboard engine mounting height should be determined by matching cavitation plate(plate over prop) of outboard with bottom of hull, directly in front of engine location. The further back from transom that engine is mounted, such as a jackplate, bracket, etc., the "rule of thumb" is to raise engine 1/2" for every foot back.

 

[NIGHTIDES]

Vero:

Yep I am on board with that info.

But the reality is that engines for the same hull, the 232 in this case, that I have seen are mounted at different heights than the rule of thumb would dictate. All things being equal, the performance #"s should be way different; a boat with an engine mounted on the top hole vs. one w/ an engine 2.25" deeper in the H20 cannot be the same.

Just trying to poll how actual engine heights people use translates into actual hull performance people experience for this hull specifically so the most optimum height can be revealed.

Come on 232 owners... come clean with your info.. thanks in advance!

 

[catch22]

Nightides, I had a single 250 OX66 on my 91 Gulfstream, (bracket). It was bolted at the lowest position. The curved lip, on top of the motor bracket, was almost resting on the grady bracket.

I was pleased with the performance. Cruise was around 28 mph @ 4400 rpm. Max was just under 40 mph @ 5600 rpm, (half fuel, light load).

 

[NIGHTIDES]

Catch22:

Thanks. You probably were using a 17M wheel as well. Nice WOT numbers..

 

[catch22]

Catch22:

Thanks. You probably were using a 17M wheel as well. Nice WOT numbers..

Yea, I believe it was a 17M.

Cruise numbers dropped quite a bit with a heavy load, (4 people, full fuel). Around 23/24 mph @ 4400. Don't know what top end was... never really opened it up when fully loaded, but every now and then, at the end of a trip, I would push it to full throttle, just to kind of "blow out the carbon". No tabs and trimmed up, I would see 39/40 on the gps.

 

[BobP]

I thought on Grady Drive models, the motor is always mounted as low as possible on bracket, per Grady HQ instructions.

 

[NIGHTIDES]

I thought on Grady Drive models, the motor is always mounted as low as possible on bracket, per Grady HQ instructions.

Surprised that only one former/current 232 chimed in on this thread. But from what I have so far is as follows:

hole one / lowest engine height: 2 boats
hole two / second lowest height: 3 boats
hole three / third lowest height: 1 boat
hole four / highest engine height: 2 boats

The bell curve on this so far is skewed towards engines being buried deeper in the water creating more drag. If this being the norm, I am curious as to just how the WOT / performance might pan out for these owners.

Bet Grady HQ wants the security in having the engines deeper to prevent blow out and cavitation complaints from unknowing operators. But in the end this may compromise how the hull can perform.

 

[BobP]

In big followng seas, the prop will tend to pull out more often if motor is higher, creating a situation where the boat is out of control and can't respond to get out of it and porpoise instead, more like like a surfboard action.
If anyone ever had this happen, very un-nerving. OK for being on a surfboard.

So safety may be an issue, that matters more than economy.

On twins, the outer motor on turns is going to naturally come out of the water higher, so it will tend to loose bite and then loose speed. Not the case with center mounted singles. So singles may be set higher, perhaps, than twins.

 

[BabyG]

Good info, sorry I can not really add to much.
250 E-tec top hole on bracket
WOT 5500 rpm 30.7 knots 150 gal 2 people and a lot of gear.
prop 17 ? do not know the size exactly.

 

[NIGHTIDES]

Good info, sorry I can not really add to much.
250 E-tec top hole on bracket
WOT 5500 rpm 30.7 knots 150 gal 2 people and a lot of gear.
prop 17 ? do not know the size exactly.

BabyG, what about the engine hole being used..?? Is that also the top one??

 

[BabyG]

its the bottom hole on the engine

 

[NIGHTIDES]

its the bottom hole on the engine

Thanks.. So she is all the way up.