Stern lifting prop for 20 MA with bracket

[bartt]

I have a 1970 20 MA with a bracket and a 200 HPDI. The boat is a little heavy in the rear and would like to be able to stuff the bow in a little more on choppy days. I have tried to put on trim tabs but the bracket does not allow enough vertical height on the transom to have them mount correctly.

I have read that stern lifting props could help. The boat current has a Power Tech SS 3 bladed prop size 14.25 x 19. I called Power Tech and they said a 4 bladed prop in size 14.25 X 18 would give me a very noticeable difference in choppy conditions as be able to get on plane at slower speeds.

Could any of you prop gurus comment if I should head on this course of action. The guy from Power Tech also said the 4 bladed prop should cost around $600 but may be able to find better deals on the web. I have done some quick searching but haven't been able to locate any? Any suggestions?
I'm trying to add some photos so you can see how the boat sits in the water.

Also on a final note, anybody want to buy some brand new Lenco trim tabs with controls new still in the box?


Thanks in advance,
Bart [image][/image]

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[eggsuckindog]

I think a 4 blade would help - just a comment with the motor set back that far sure looks like the motor height could come up - that would change the attitude of the drive force.

[Bushwacker]

A "little heavy in the rear" is probably an understatement! These boats were designed for ~300 lb motors hanging on the transom, so when you put a 400+ lb motor on them and then move it 30" aft, it's no surprise that they don't perform as designed! Don't know what your motor weighs, but it's probably similar to my E-Tec which is about 427. My Seafari is not as stern heavy as a cc, but a 4 blade prop still made a big difference. Adding an additional blade will give more stern lift, even if it's the same blade configuration as what you're running now.

The price PowerTech is quoting you is for the fancy shock absorbing hub system (OFS?) that Marcus says is needed for the 4-stroke yahamas. Don't know if the 2 stroke yamaha needs them also. I just bought a 4B SS PowerTech prop for $315 that uses the Michigan 2-piece hub system, similar to Merc's Flo-Torque system but beefier and better quality. They also quoted me a 2X higher price for the fancy hub, but said it wasn't needed for the Evinrude. They don't want to undercut their dealers, but usually you can find one of their dealers that will sell for $20-30 below list. I started out with an aluminum Michigan Vortex 14x20 4B which was only about $130 and worked great but was a little too much pitch, so had it repitched to 18" and it's about perfect; can plane with a very heavy load at 12-13 mph. I also have a SS 4B 14.125 x 20" pitch Michigan Apollo that I use for light loads and better fuel economy. Both Michigan props seem to have more stern lift than the PowerTech, even though they're not advertized as stern lifting props. I can plane at lower speeds with them and trim the motor higher before it starts to porpoise. The 15x15 PowerTech does have an awesome hole shot however and seems to be reasonably efficient - just completed a 235 mi cruise with it and averaged 4.3 mpg for entire trip with a total load of about 3800 lbs!

You just have to notch the bracket to mount the trim tabs, which Don Herman did when he installed my bracket. My tabs are Bennett's; don't know how the dimensions compare to the Lenco, but they're over 30 years old and they still work perfectly. Looks like your bracket doesn't have much flotation or planing surface to help it get on plane, so the tabs should also help your low speed planing.

[Fr. Frank]

A 4 blade is inherently more of a stern-lifter than a 3 blade. The Rev 4 and Trophy 4 are both good in addition to the Power Tech.

[McGillicuddy]

Not really a prop guru but...

A "little heavy in the rear" is probably an understatement! These boats were designed for ~300 lb motors hanging on the transom, so when you put a 400+ lb motor on them and then move it 30" aft, it's no surprise that they don't perform as designed! Don't know what your motor weighs, but it's probably similar to my E-Tec which is about 427.

In fact depending on the model it's 475 to 539lbs. Sir, dare I say it, your seacraft is seriously suffering from stern squat Check the model of your current ptprop. By dimensions and appearance I'd guess its a PTC3 or RAS3, or an SFS3 ("Baby OFS"). I may be way off, but it should say on the prop. Check it to get an idea of what the prop is designed to do.

The PTC and RAS are a bow-lifters like the Rapture or Stiletto. Definitely not what you want. The SFS is similar to the Yamaha Saltwater series and would probably be fine if not for the extra 175 lbs set 30" off the stern like a bully on the teeter-totter. That in a four blade might help you.

Even better, you might consider an MQS3 which is a stainless stern-lifter in the mold of Mercury's Black Max. I have seen them on a website for a little over $300, plus the hub. It's a 14.00" wheel in 19 pitch and 14.50" in 17", and it is considered easy to turn. The the extra blade surface area should help to lift that heavy stern load. I am not sure if they make a 4 blade MQS for your motor but its certainly worth ascertaining. but I think the MQS is less costly and would better serve you. Also their SCE3 and SCE4 are stern-lifting semi-cleavers that mimic Yamaha's own semi-cleavers. Probably also decent choices. Good Luck

[Old'sCool]

I installed a Solas 4 blade 17p on 22' Whaler w/225 Yam. It made a world of difference! I could plane at a much lower speed and gave up very little top end. I think you should keep the tabs and modify the bracket so they fit.

[fdheld34]

So many choices in prop configurations especially when engine weight has increased compared to what hull was designed for!!!. My head is spinning from all the great above input. Again printed out above info for my Classic Seacraft "Folder of Knowledge". Beats having to search in future........

I think you might need to hold on to your tabs as well!!!!!!
-Fred

[bartt]

Thanks to everyone for their very helpful insights.

In response to McGillicuddy my current prop is a PTC3 in which you state is a bow lifter, so getting more of a stern lifting prop should be a big help. All in all, the boat handles pretty well as is, but as I said in my 1st post it would be nice to stuff the bow in more at slower speeds on choppy days.

In response to Bushwacker, thanks for the info. I think I will try the Michigan 4 blade Alu. I found them for about a $130 on the web.... somewhat of a cheap way to experiment. And to EggSuckingDog, I will fool around with the motor height as it has a manual jack plate and should be easy to try different positions.

For all those suggesting I keep the tabs and notch the bracket, I just don't think it is physically possible to do. I'll attach a pic so you can see what I'm dealing with. If I mount the tabs close to the sides of the tub of the bracket I would have just enough room to mount the top end of the piston just below the bracket edge. And the tab would have to be at the same level plane to the bottom of the boat, I was told proper mounting of the tab should be above level when fully retracted. I was also told the tabs mounted in this position would be to close to the center of the boat and would disturb the water for the prop. I just don't believe I'll have enough verticle height on the transom to move the tabs further to the outsides of the boat even with the bracket notched. See the pic below. Any thoughts or suggestions would be very welcome. Maybe I'm just not seeing it the right way.

Thanks,
Bart

[MasterBaiter]

If you decide you are not going to use the Lencos send me a PM with specifics. A friend of mine might be interested.

[Bigshrimpin]

Sell the HPDI and buy a Yamaha 130 or a mid 80's Merc 200 (with a mirage plus or Rev4) both are the same weight 350/360lbs. You'll have enough $$$ left over for a $5000 gas card and solve your problem at the same time.