Prop's performance & trim tabs - need help

[peterb]

Ok all, here is the lay of the land.

I have a 23' 1972 SeaCraft w/twin Yamaha 200 HP OX66's. The motors are on a full flotation bracket. Also, I have Bennet 12 x 12 trim tabs.

The boat is definately stern heavy.

I have two sets of Yamaha SWS series props (21 x 14.75 and 19 x 15.25)

The engines are mounted at the mid level on the bracket (I have had them at the top level and bottom level as well)

I have two problems.

First, the boat rides (particularly into a head sea) ass heavy. I used to have another 23 SeaCraft w/twin Yamaha 150's (no bracket) and it was a better riding boat into a head sea. That setp had 17" SWS props.

Second, the prop's definately kick up some water when the boat is on plane.

Using the 21" props I get better WOT speed (up to mid 50's) and slightly better fuel economy. The 19" props probably give me a slightly better ride in snotty condition (because they enable me to plane at a slightly slower speed).

Any ideas?

I have been thinking about the following

Purchase and install the drop fin verion of the Bennet trim tabs.

Looking for another set of props (4 blade) that raise the stern a little.

Any specific feedback would be greatly appreciated.

Thanks,

Peter

[Bigshrimpin]

Peter - Try raising the motors a few holes before switching to different props. I had a similar porblem when my motor was mounted too low. This photo was taken while the boat was coming out of the hole, but you can see the spray. I raised the motor 3 holes and I picked up 400rpm and there's no more spray. Mirage Plus or Rev4's will help. But . . . moving weight forward, bigger tabs, and raising the motors will probably make a bigger difference.

[peterb]

Thanks for the feedback. I already had movet the engines up to the top mouting point, and I moved it back down one notch because the prop's count come out of the water in rough seas.

[Briguy]

Peter, there is a guy on the thehulltruth forum called propgods. He could recommend a stern lifting prop. I have twin 115's 4 strokes on my bracket which weigh 416lbs each. I guess they are in the ballpark of your motors. Also can you move batteries forward? I did think your boat rode bow light compared to mine for sure. Mine runs perfectly flat once i got the props dialed in correctly. I run 24" stiletto props. 4 blades may be the ticket.

[Fr. Frank]

Peter, Tim's right about motor height. You need to go as high as you can without ventilating at neutral trim in medium seas. (You shouldn't be on plane in heavy seas). That said, you've got a lot of weight hanging 2 feet aft of your true planing stern. You REALLY need sternlifting propellers.

Tim's right about which props work well, too. I would only add to consider the PowerTech SCE4, PTC4, & OFS4 props. The OFS4 is very similar to the Mirage+, but a 4 blade, and the PTC4 is similar to the REV4. The SCE4 is like the old Yamaha semi-cleaver, but even better. It's very good for high-speed running offshore in a swell, as it can run partially surfacing before ventilating. The SCE4 does sacrifice some hole-shot performance in favor of it's performance in seas.

[peterb]

Thanks for the feedback.

I believe that my two motors weigh over 450 pounds each, and when you add the bracket that is a ton of weight.

My two oil tanks are in the enclosed transom and the batteries are under the console.

I really don't care about WOT speed nearly so much as the comfort of the ride (especially since I am going offshore more now).

Brian, I saw that same add about propgods. Also they will let you test put propo I think before buying them.

Thanks again

Peter

[FELLOW-SHIP]

Hi Peter

You also talked about the Bennett tabs. There are a few guys that have switched to the 3” drop fins for the same problems you are having. We sell a little add on Kit to convert your standard 12” x 12” to a 12” x 12” drop fin. You would have to drill some holes in your tabs and bold the drop fin part onto your tabs. The part number is DF12 and you can order them from anywhere you get your marine hardware. They would be a Lot cheaper than replacing the whole Tab. If you would like to talk about it just call Bennett Marine and ask for Mack.


Fellow-Ship


Just for the Grins

[peterb]

Mack,

You have made my day. I have dual acuators on each tab so I would much rather buy the kit.

I will definately call you.

Also, everyone else, thanks for all of th 4 prop advice. Know I just havt to fiure out if I need 17" or 19" pitch 4 blades.

Peter

[gofastsandman]

Peter,
Merc has a prop selector program on their site. I`ve called Powertech and prop gods and they were very helpful too.

Denny,
You did tell me it was an Apollo not a Rev 4....... As for mpg , I only know it`s not pretty. I don`t have the temerity to do the math. Would Boysen reeds help? I`m spinning 5200 full fuel and light load w/ a 15 3/8 x 17p mirage +. `96 rude 150 w/ 90 #`s comp across the board. Oh, vent plate 1" up.

Fr Frank, thanks for the explanation, I think. It`s starting to make a little sense. I did say a little.
All the used powertechs I`ve seen 4 sale have been thrashed. The mirage + did marvelous work with the attitude , but as Denny said it does blow out. Lost a lot of positive trim ability, which is a concern in a head sea. So I will keep looking for a good 4 blade.
Thanks,
Sandy

[peterb]

Ok, here is where thing stand

First, I pulled the boat out of the Keansburg, NJ slip (to get it ready for the late fall bass run, plus tog fishing down at Barnegat Light).

Here is a snapshot of the Bennett tab setup. The tabs are 12" x 16" (the 12" tapes down to 10").

Question for Mack. Can I get the drop fin kit for these tabs? If so, what is the part number?

[image][/image]

[image][/image]


Second, I spoke with Altantis Props out of Mt Laurel, NJ. I gave them the appropriate boat and motor info (such as perf #'s with my current prop sets). They have some ideas that they want to bounce off of the Powertech guys (that's where I am leaning). They should get back to me early next week.

I will keeo you all updated.

Peter