Permatrim---thumbs up or thumbs down?

I had them on my 16 and it was if they were designed for the C-Dory 16. The difference was amazing in every aspect. I ordered one for my 22 a few days ago (which has trim tabs) and Shipyard Marine is really nice to deal with. I didn't have the order in any time and I got a confirmation in a few hours that the item had been shipped. I'll try to do some before and after tests and record RPM and MPH at various ranges for comparison. I don't expect there to be much difference in this. I'm expecting the permatrim to improve the side to side trim. Now when I use my trim tabs to compensate for side to side trim preformance suffers due to the drag created by the tabs. I hope to be able to use less tab to achieve side to side trim while planning with the permatrim installed. My boat with a Suzuki 90 full tanks and 3 batteries in the lazarettes is pretty heavy in the stern.
 
While I don't have any yet, it would seem that Permatrims would really enhance a twin setup. In fact, due to the fact that they have leverage, and a lot of it, they maybe even better than factory trim tabs. If you were financially challenged and could only afford one or the other (trim tabs, or permatrims on a twin) which would you get?
 
TyBoo":3examu6b said:
Oh, I've been snookered before. The Lenco trim tab guys got me good and that's why I am trying the Permatrim. My tabs are scarcely adequate and I'm hoping the foil will let me use the tabs more for the lateral and less for the bow down stuff. I'm also hoping it will do it without costing any speed because I am kind of underpowered with 130 on my heavy old boat. We'll see.

I do have a bit of faith in it helping, though.
PermaDork.thumb.jpg
I was so sure I didn't even try the PermaDork before buying the real thing.
Click to expand...

So what was the answer, Mike? Are you happy with the Permatrim?

Roger
 
I don't have a great explanation for this but - we just finished three weeks taking our boat from the Hudson River up to the Georgian Bay.
We were loaded with 5 people, gear, full to half fuel. Speeds were 10 km/hr to 25 knots.
With the load we required a lot of trim with our trim tabs and permatrim.
I noted one day that one of my eight stainless steel bolts between the av plate and permatrim had sheared, closer inspection showed that 6 of eight had sheared and the remains of the bolts were held in place by the adhesive we had used between the AV plate and permatrim.
Some of the bolts were sheared on the nut side, some on the slotted side.
The only two bolts not sheared were the two forward. The permatrim plate was still solid - I couldn't flex it.
I replaced the bolts with spares and will have to see if it happens again.
I assume it was caused by some flex between the av plate and permatrim or perhaps the stainless bolts were weak and over tightened when I installed my permatrim although I tightened everything only with hand tools.
The message is you might want to check and be sure everything is intact in your installation, a quick glance could be deceiving as the bolts are held in place by adhesive and you could miss a sheared bolt.
Eric
 
Thumbs Down! I installed Permatrim on the Half/Pint (22 cruiser w/75 4 stoke Merc)

On the ICW with calm water top speed decreased by 6 MPH from 30 mph to 24 mph, cruising speed rpm increased from 3,200 to 4,000, WOT decreased from 5,800 rpm to 5,200 rpm, lots of drag. Haven't checked fuel flow but its got to be higher

On the plus side the trim is more sensitive and the low speed handling has improved.

I have been running this boat for 12 years without a Permatrim & will continue to, so if anyone wants one for a merc. make me a offer.

Sam
 
You may now be dragging with your trim tabs too much down. But, you may know that. Most Dorys don't use trim tabs much with the Permatrim. Of course you know that will cause considerable additional drag when run with the Permatrim.
 
I recently installed Permatrim on my 22 Cruiser. This replaced a Doel Fin I've been running for 8 years. I run with a 70 hp Suzuki, a little underpowered but paid for, low hours and perfectly dependable. Permatrim instructions stated you could run the motor a bit higher, so I raised the motor 1 1/2 inches while I was at it.

On a trip to 3620 ft. Lake Powell with the same (too heavy) load as previous trips I was able to increase prop pitch from 13 to 14 inches. Top speed went up 2 knots. I believe that getting the stern up was the reason, and raising the motor had something to do with it. Fuel mileage was unchanged. Control was about the same except one trim combination that made steering a little too sensitive. The biggest plus was being able to get the bow down more...a lot more...when needed to handle nasty chop. I was able to maintain speed through various chop/wake conditions that I would have had to slow down for before. So, in my opinion its a good improvement at a reasonable price.

With that said, there are a couple of negatives. I usually fab up my own parts, but I was short of time, and all the usual excuses. Hey, just dial and give them the card number! In my installation, the Permatrim did not match the AV plate well. The Permatrim has a little angle to it, and the AV plate is flat. This leaves a gap...not good engineering practice. You have 2 choices: Tighten the bolts to unreasonable levels or fill the gap with some kind of goop to keep water from collecting there accellerating corrosion. The better choice seems to be fill the gap and not chance breaking the AV plate. I used 4200. Negative #2 is the dissimilar metals corrosion problem, in this case stainless and aluminum. In order for this not to occur, the 2 metals must remain perfectly dry. Perfectly. Anyone who has worked on their aluminum sailboat mast can tell you what happens...the aluminum goes away around stainless fittings and fasteners. Salt water really speeds this up. So the question is, which will go first...the Permatrim or the outboard? I put anti-corrosion paste around the ss bolts, and the boat lives on the trailer well away from salt water so I should be in good shape...for awhile. Time will tell, and I'll bet our saltwater Brats will have the first reports for us.

Have fun,

Roy
 
Rick from Foggy Dew installed my new Permatrim this afternoon. We did a little test run and I am glad to report that I am very happy with the results!
Much faster hole shot
Very tight almost sports car like control from start to top end
No loss of top end speed 33 mph [very heavy loaded]
No pounding untill we hit big chop. Even then we were fine at @22 mph.
No trim needed to bring down the bow. I suspect that means better mpg without the tabs dragging.
150 hp Zuki with 16" 3 blade SS prop 18 pitch
Permatrim is a real keeper.
Thanks again Rick! :thup
 
Eric (Helm) wrote:
I don't have a great explanation for this but - we just finished three weeks taking our boat from the Hudson River up to the Georgian Bay.
We were loaded with 5 people, gear, full to half fuel. Speeds were 10 km/hr to 25 knots.
With the load we required a lot of trim with our trim tabs and permatrim.
I noted one day that one of my eight stainless steel bolts between the av plate and permatrim had sheared, closer inspection showed that 6 of eight had sheared and the remains of the bolts were held in place by the adhesive we had used between the AV plate and permatrim.
Some of the bolts were sheared on the nut side, some on the slotted side.
The only two bolts not sheared were the two forward. The permatrim plate was still solid - I couldn't flex it.
I replaced the bolts with spares and will have to see if it happens again.
I assume it was caused by some flex between the av plate and permatrim or perhaps the stainless bolts were weak and over tightened when I installed my permatrim although I tightened everything only with hand tools.
The message is you might want to check and be sure everything is intact in your installation, a quick glance could be deceiving as the bolts are held in place by adhesive and you could miss a sheared bolt.
Eric
Click to expand...
Before I put mine on (CD-25 with twin F80's) Shipyard Marina cautioned me not to mount the Permatrims too far aft on the AV plate, could cause bolts to shear from the stress. So I tucked them up as far forward as I could but to avoid interfering with the differential oil vent plug at the forward edge. So they have had similar problems. In your case I'll bet the aft most bolts became stressed and eventually failed, thus putting additional load on the next pair forward causing them to fail and so on.

If it were me, I'd add 4 more bolts in between the last 3 pairs (2 between each) to double the strength rather than just putting another set of SS bolts on and seeing what happens. I doubt that one set of SS bolts will have that much more tensile strength than another. Just my 2c.

By the way, I'm very happy with my performance increase and steerability (engines able to be tilted much more horizontal than before). I use them at a fixed angle, maybe 15 deg (est), then use my oversized trim tabs for additional trim, fore/aft or lateral -- they don't need much thus reducing the drag effect.
 
Steve I think you are right about flex in the permatrim shearing the bolts.
With full fuel, and water, and five people with gear for three weeks we were pretty heavy and I had to use 100% on the trim tabs and quite a bit of down trim on the motor to keep our planing speed up in the low 20 knot range until we had burned off 1/4 to 1/3 of our fuel.
I couldn't flex the plate by hand and the boatlife adhesive seemed intact.
The plate is mounted as far forward as possible so I think your idea of adding some more bolts is probably the fix.
Thanks
Eric[/img]
 
The instructions that came with Jeff's plate say to use all 10 bolts, and that not following the instructions will void the warranty. They were very specific about bolt spacing, edge distance, etc. Food for thought. I mounted the plate as far forward as I could without hitting the radius of the motor at the aft edge. Backed it off from there just a hair.

I was pretty impressed with the performance.

No problem, Jeff...it's always fun to drill holes in someone elses' engine! :shock: No pressure there!! I didn't do it myself, either....Jeff helped. It was a fun project.
 
You might not need extra bolts. There's a factor of two variation there is in stainless bolt tensile strength depending on what type of bolt you buy. In stainless bolts for example a 3/8"-16 x 1" bolt can very in tensile strength from about 70,000 PSI (for unrated bolts) to about 140,00 PSI for ASTM rated bolts (shear strength is not specified but is estimated to be about 60% of tensile strength). Also, fine threaded bolts generally have a higher shear strength than std. or coarse threads. So, take a look at the markings on the bolt heads to determine what grade you used. If they were grade 8, you can do much better without exotic materials. But, if they were unrated or a lower grade, replacing them with a high grade bolt might solve the problem.
 
OK You guys sold me.....I just ordered a set....for my Yamaha 40 twins...I never have been much impressed with the motor trim so this should really make a difference..... now if I could figure out some way for my automatic trim tab controller to manage the trim tabs and the permatrims at the same time I would be set...

Joel
SEA3PO
 
Thanks for the ideas Roger, I think the machine screws came with the plate but I can't remember. I will try to find some rated stainless machine screws to take back up to the boat with me in August and just try replacing all the bolts since it would be hard to drill the plate with the boat at the dock.
It could be I just over torqued the bolts, the instructions say only 10 foot lb of torque and I didn't use my torque wrench just hand tightened.

Eric
 
Half/Pint":1rleuv64 said:
Thumbs Down! I installed Permatrim on the Half/Pint (22 cruiser w/75 4 stoke Merc)

On the ICW with calm water top speed decreased by 6 MPH from 30 mph to 24 mph, cruising speed rpm increased from 3,200 to 4,000, WOT decreased from 5,800 rpm to 5,200 rpm, lots of drag. Haven't checked fuel flow but its got to be higher

On the plus side the trim is more sensitive and the low speed handling has improved.

I have been running this boat for 12 years without a Permatrim & will continue to, so if anyone wants one for a merc. make me a offer.

Sam
Click to expand...

Hi Sam,

I am sorry to hear about your speed loss with the addition of the Permatrim. This is 99.9% of the time caused from the engine being mounted to low on the transom. If this is something you would like to correct and reap the benefits of the Permatrim, we can work it out on the site here, or you can call or email me. Even if you do not want the Permatrim, you should still consider raising the engine to a height were the AV plate on the engine is level with the bottom of the boat.........directly in front of the engine. I have a feeling yours is below, and when you add a Permatrim, it will create more drag....hence you speed loss.

Raising the engine is not hard to do. Most engines have slotted lower mounting holes. Its a matter of removing the top bolts and loosening the lower ones. Then installing and sealing the upper bolts, then removing the lower bolts.......resealing them and tightening them back up.

Every hole on the bracket is app 1".

There are several ways to do the heavy lifting of the engine. Of course a lifting device works well, but in a pinch with the boat on the trailer you can do it with no lifting equipment. What you would do is lower the tongue all the way down to the ground. Then tilt the engine down. Then put some small blocks of wood under the engine lower unit fin. Then raise the tongue of the trailer up with the jack. This will lower the fin onto the blocks and then eventually with more jacking will raise the engine. It works well with two people.

Thanks,

Andy

andyjr@shipyardisland.com
1-800-213-3323
 
As far as the bolts snapping........I have found thru my own installations on local customers engines that this caused from simply over-tightening of the bolts and nuts on installation. When we first started using them 4 years ago, I was seeing this happen with my own installs.

It really does not take much effort to snap/twist a 1/4"-20 SS bolt. If they are snapped near the head, this most likely is the cause. When I install them, after tightening them all down snug, when the Permatrim hits the AV plate it really does not take much more tightening after that. With aluminum on aluminum, you are not going to compress the material like you would with wood, or even fiberglass.

If you need extra bolts, please shoot me an email and we will ship those out to you at N/C. Please include you full name in that email. We should have your address's on file.

Thanks,

Andy

andyjr@shipyardisland.com
1-800-213-3323
 
Rogerbum wrote:
You might not need extra bolts. There's a factor of two variation there is in stainless bolt tensile strength depending on what type of bolt you buy. In stainless bolts for example a 3/8"-16 x 1" bolt can very in tensile strength from about 70,000 PSI (for unrated bolts) to about 140,00 PSI for ASTM rated bolts (shear strength is not specified but is estimated to be about 60% of tensile strength). Also, fine threaded bolts generally have a higher shear strength than std. or coarse threads. So, take a look at the markings on the bolt heads to determine what grade you used. If they were grade 8, you can do much better without exotic materials. But, if they were unrated or a lower grade, replacing them with a high grade bolt might solve the problem.
Click to expand...

Good point Roger! I'm always learning something everyday. I didn't realize there were different tensile grades of SS (available to the public and not just NASA or the military). Thanks for the clarification. I'll bet Andy is right on though, he's had lots of experience with them, SS (standard grade) yields at a surprisingly low torque--and many times you don't even know it tell much later. All is worth it though to keep those Permatrims happy!
 
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