2520 XL Permatrim/4 blade prop

[albiejunkie]

I posted this on NJAngler's post about his 2110 redo, sorry NJAngler! This belongs here.
Some of you have made mods to get your hull to plane at lower speeds. I would love to get my boat to hold plane at 3400. Sea conditions in my area (RI Sound, BI Sound) are typically 2-4 foot, SW winds 10-15mph. Lower planing speeds would make my ride WAY more comfortable.
I have a 25xl with a 250 yammy 4s swinging a 15.5 x 17 mirage plus 3 blade. Need about 42-4400 to hold now. Just bought the boat and have run her 4 or 5 times now and that is really my only complaint right now. It will spool up to 5900 and 39 mph with just me, 1/2 tank (85 gallons) and all my gear. (This will be my normal condition)
I have those pockets for the stock 12 x 12 tabs and would like to try something else besides hull surgery.
Anyone have the same boat and engine that have done the permatrim and/or 4 blade? And, how did it do?

 

[eyedoc]

Albie,
I have a 2510 XLD with twin 150’s. I put Permatrims on after a few weeks
of having the boat, after experiencing the ‘Parker squat’. They made a HUGE difference in handling and lower speed planning. I am really glad I did it.
PM me if you need more info.

 

[albiejunkie]

Thanks for responding eyedoc.
I went out yesterday and noticed vibration as I was coming out of the hole until she got up. Its always been there but now I'm trying to notice everything. I also observed that the cav plate was below the surface when running at about 4700/27 mph.
I think I should raise it before I do anything else, right? Motor can go up as much as 2 holes, so mounted in 3rd hole?

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[PKS1801]

I don't get the whole Permatrim thing, except for hole shot. The anti-ventilation plate is supposed to be clear of the water on plane, right? And with all the talk about raising motor height on this site, that should be even more the case, so how does a thin piece of aluminum right above, or below, the AV plate do anything at speed, when it should be out of the water? And what is the engine trim at lowest planing speed?

 

[eyedoc]

I have left my engines at the deepest hole (#1), as sent from the factory. I installed the Permatrims and found not only a quicker settling of the bow, but also less wandering and porpoising. The wider planning surface of the Permatrims provides more lift, therefore the stern stays higher and the boat stays on plane at slower speeds. The cavitation plates are too small to provide adequate lift, especially when the engines are on a bracket.
I am currently running 28 mph at 4000rpm with 1/2 tank of fuel and myself on board, getting approx. 2.0 -2.2 mpg.

 

[grouperjim]

On a bracketed DV Parker hull the permatrim defines the running attitude of your hull. At cruise it has enough lift to bring the A/V plate very close to the surface. Relatively speaking, keep your motor in the factory mounted top hole (deepest position) and the bow will ride the lowest, lower the motor and the bow will ride higher........your preference. Personally, I like my bow down and boat level as possible in the water.

I suggest changing one variable at a time. Leave the engine height alone......permatrim first. On a twin engine Parker like mine, trim tabs rarely if ever get used. On take off I use 2 bars of the engine trim only then as I plane out 3 bars on the engine trim. I run with 3 bars of engine trim at cruise. The permatrims cause no hit on fuel economy. Trim tabs on the other hand kill fuel economy.

 

[Antidote]

I’m pretty happy with my numbers with two adults onboard. Twin Yamaha F 200 XCA mounted on the third hole from the top. No permatrim needed. Set you engines to the correct height then start adding things if you aren’t happy.


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[PKS1801]

The anti-ventilation plate is not there to provide lift, it is there to prevent your prop from sucking air. If adding the increased surface area of a PT only brings your AV plate "very close to the surface", you are dragging too much lower unit through the water. Water rises as it clears the transom, and there is a rule of thumb for how much you raise your motors for every inch of set back on a bracket. Unless the design of the bracket already raises the motor significantly over where it would be if transom mounted, I can't believe that it would be the most efficient in the lowest position.
I think Antidote has it right, you start with motor height, not add-ons. Now if someone told me that a PT, on the surface, allowed you to raise your motor by preventing ventilation at that height, I might buy some of that.

 

[grouperjim]

The anti-ventilation plate is not there to provide lift, it is there to prevent your prop from sucking air.

You are correct.......the A/V plate is there to provide A/V. As is, it also functions as a control surface to prevent porpoising. A Permatrim enhances both of those functions.

In this case, modification of the A/V plate with a Permatrim will dramatically compensate for the lack of hull planing surface area due to engine setback on a bracket. The plate provides lift which greatly alleviates "Parker Squat" which is common to all bracketed DV Parkers.

You really can't understand the incredible difference a Permatrim makes with regard to alleviating Parker squat and running level at much lower RPMs until you have run identical boat side by side one with the mod and one without.

Do a search on this site and you'll see many testimonials from Parker owners.

 

[albiejunkie]

I think what I'm looking for is just a lower planing speed.
I'm curious if anyone with a similar setup to me (2520 XL with F250 on a bracket) has added a Permatrim and/or 4 blade to accomplish this.
Went out today for a few hours running around in honest 2-3' chop with a 3' swell under it. Ran it at different rpm's trying to figure it all out.
I had 75 gals fuel, 2 big adults, all my fishing gear, 60 lbs ice, plus I carry an electric pot hauler at another 140 lbs., and the kicker motor. So I have a lot of weight behind midpoint.
4700 RPM gives me 27-28 mph at 2.3 mpg. I'm very happy with that for a fast cruise.
I know though that there will be days that aren't this nice out that I'll be running in and I will want to slow down but stay on plane.
Right now, if I let it go below 4500 RPM it will fall off.
I gotta say, I was impressed with the way she handled going into it and with it. However, it's no deep V.

 

[albiejunkie]

Grabbed a used Merc Rev 4 17 pitch on Friday.
Whenever it stops pouring around here I'll try it out.
Hoping to use the lift to keep me on plane at lower RPM's.
Also hoping to prevent drilling holes...

 

[albiejunkie]

Did some preliminary tests today . So far I like the results. Smoother and quicker hole shot, more responsive at the dock, and I'm able to hold plane at 4200 (22 mph) instead of 4600 (27 mph). Top speed is 38 mph at 5950 rpms, which is 50 rpms more and 1 mph less. I can live with that. Had all my gear, 135 gallons fuel, just me aboard. Typical day but without the 100 lbs ice. I used no tabs ( I have recessed 12 x 12's), just motor trim.

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[albiejunkie]

Roasted the lower unit on my F250. So while I wait for the new replacement to get here, I'm going to raise the engine one hole. With the 4 blade and motor raised, I'm hoping to see better fuel economy...

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[albiejunkie]

Got my new lower unit installed and took it for a ride yesterday with the rig raised 1 hole. It is now in the 2nd to last hole from the bottom, so 3rd hole?.
The only differences I saw were slightly better fuel economy at cruise (2.3 mpg at 4700 rpm, 27 mph vs. 2.2mpg at same rpm and speed) and no side spray coming from the engine while running.
I was not able to confirm cav plate position as I was alone and running through a crowded lobster pot field.
I did notice that I could'n't trim it up as much as it would blow out, but I feel I didn't need to trim it out as much as before anyway.
No changes in speed at any RPM. The fuel economy saving is nicer though.
So far, so good.
So, what would a Permatrim do for me at this point?