Jack Plate Experts - Question for You

[Bruce]

Hi Guys, I am currently getting all the stuff I need to attach my new Detwiler Manual 6 inch on the Water Jack Plate on my 92 Pulse 170 with a 120 Evinrude weighing in around 375 lbs.

I won't be starting it until the Spring time but I want to have everything ready to go. The last week or two I have learned WAY TOO MUCH about bolt grades etc etc. There are a couple of different schools of thought with respect to what bolts to use but I decided to go with coated Grade 8 bolts, with Stainless Steel flat washers, Stainless Steel lock washers and Stainless Steel Nylok nuts with Anti Seize to boot. The boat will always be in Fresh water so I decided against going with the Stainless Steel bolts with Brass Nyloks.

My question is about the use of a Transom Washer Plate for the top set of bolts, do I really need one. I can justify both sides of the fence on this one. Currently, the motor's top bolts use the existing plate's that I presume the factory installed which measures roughly 2 inches by 3 1/2 inches with 2 different sized washers. As we know the Checkmate transoms are very thick as long as no visible damage appears and my 375 lbs of motor is well within an acceptable range, even with a 6 inch Jackplate I figure. The other side says, what the Heck, Over kill never hurts anyone. I have noticed there are 2 basic types of these available, one made of 6061 T6 Aluminum alloy (CMC) and ones that are cast aluminum. I was able to buy a cast aluminum one made by T H Marine at Bass Pro Shops for $23.00 Canadian so I bought it.

So, the million dollar question is,

Do I return the Cast Aluminum one and buy a 6061 T6 Aluminum alloy (CMC)version.

OR

Return the Cast Aluminum one and just go with the factory plate's that are currently there.


As always, Thanks for your thought's


Bruce

[Bruce]

Hi Guys, I am currently getting all the stuff I need to attach my new Detwiler Manual 6 inch on the Water Jack Plate on my 92 Pulse 170 with a 120 Evinrude weighing in around 375 lbs.

I won't be starting it until the Spring time but I want to have everything ready to go. The last week or two I have learned WAY TOO MUCH about bolt grades etc etc. There are a couple of different schools of thought with respect to what bolts to use but I decided to go with coated Grade 8 bolts, with Stainless Steel flat washers, Stainless Steel lock washers and Stainless Steel Nylok nuts with Anti Seize to boot. The boat will always be in Fresh water so I decided against going with the Stainless Steel bolts with Brass Nyloks.

My question is about the use of a Transom Washer Plate for the top set of bolts, do I really need one. I can justify both sides of the fence on this one. Currently, the motor's top bolts use the existing plate's that I presume the factory installed which measures roughly 2 inches by 3 1/2 inches with 2 different sized washers. As we know the Checkmate transoms are very thick as long as no visible damage appears and my 375 lbs of motor is well within an acceptable range, even with a 6 inch Jackplate I figure. The other side says, what the Heck, Over kill never hurts anyone. I have noticed there are 2 basic types of these available, one made of 6061 T6 Aluminum alloy (CMC) and ones that are cast aluminum. I was able to buy a cast aluminum one made by T H Marine at Bass Pro Shops for $23.00 Canadian so I bought it.

So, the million dollar question is,

Do I return the Cast Aluminum one and buy a 6061 T6 Aluminum alloy (CMC)version.

OR

Return the Cast Aluminum one and just go with the factory plate's that are currently there.


As always, Thanks for your thought's


Bruce

[Craig]

I had 8" setback with a 300 Merc on my Pulsare and I reused the factory plates. If I remember correctly, they were on all 4 bolts, not just the top 2...If I would have went to 10or12", I think I would have done something different. What is your total setback?

-Craig

[The Mate]

Hello fellow Check Mate fanatics!

I am thinking of putting a Jackplate on my TriMate and was wondering if anyone had some recomendations for setback and a good brand! As of right now the prop shaft is WAY to low! Thanks! http://checkmate-boats.com/6/ws/,s,8626072361/Graemlins/thumb.gif

[Bruce]

Hi there, I spoke with Mike at the factory this morning and from his perspective, the transoms built in the 90's and onwards are much stronger than those in the 80's. His recommendation is to use the factory stainless steel plates, due to the extra bracing etc during construction, you won't run into any troubles.

Craig, your right, it does come with 4 plates, 2 on the top and 2 on the bottom. I thought perhaps that the "main" concern was the Top since I figure the majority of the "force" will be pulling the motor from the Top and pushing the reacting force towards the bottom.

The total setback is only the 6 inches from the Jackplate plus the 1 inch motor mount if your counting that.

The Mate, the amount of setback can vary from boat to boat, I'll leave that one alone, I am in no position to offer any decent advice on that subject. As far as what Brands, from the factory they tend to go with CMC, I chose the Detwiler because of the fact that you can adjust it on the water with only one bolt and a locknut. On the CMC's there are additional bolts on either side to adjust as well. The other question you have to ask yourself is Manual or Hydraulic, Hydraulic being sometimes 2 or 3 times the cost.

I have only learned a little bit, do some searches on this board and you'll find some other perspectives. I'm sure some of the others will offer up their opinions as well.


Bruce

[175checkmate]

On the transom washer, both work well and you would have no trouble running them. The factory part is a great piece also and you already have one.

The Mate: Jack plate on a trimate. The one I ran before I started the resoration project was a homemade hyd unit with no set back. I am going with 6" to start and see how well it works. I have a 2.4L 200+ merc hanging off the back. I have a 2 piece plate that I bought used and decided that I am going to get a one piece unit. I want to be able to adjust the plate on the water and that is hard to do with the 2 piece plate. I have a set of 2" spacers that I am going to try after I base line the set up.
I will also be trying a few things with the lower unit as well. I am going to test the following.
1, Factory water pick-up
2, top 2 holes pluged and engine set higher (water PSI dependant.
3, Install a Bob low water pick up and nose cone and jack it to the moon.
Should be interesting to see what differance it makes.

[JW]

Hey Bruce, I've run both the factory little plates and the full width plates on the inside of the transom. Basically, it boils down to looks on a thick Checkmate transom. I think the full width upper bolt plate looks cool http://checkmate-boats.com/6/ws/,s,8626072361/Graemlins/thumb.gif
For the lower bolts, my Checkmates have had a brace down there that kept me from running the full width plate anyway, so I stuck with the factory 2"X3" plates.

[Bruce]

Hi JW, as you said, it looks Cool and we all know that perception in most cases is thought of as reality. You guy's with the Pulsare's better watch out !!

The only concern I have with the Cast Aluminum one I bought is the overall strength, it has the 2 Bolt holes recessed. I don't want to jeopardize the integrity of the setup by using a plate that may allow the bolts to eventually work their way through over time.

I'm thinking, if I want the "cool" affect, I will return the cast aluminum one and get the CMC, made of the 6061 T6 Alloy.


Decisions Decisions Decisions


Bruce

[JW]

I made my own once. I bought bar stock 2" high by 18" wide by 1/2" thick and drilled my own holes, then painted it black. THICK AND STRONG!

[Bruce]

Hi there, I posted a similar message over on S&F as well with respect to my perdicament with the transom plates. Based upon this little chart I found, the Aluminum Alloy plate (6061 t6) is stronger.

Web site is

http://www.tawvehicle.com/alloyperf.htm

GENERAL ALLOY PROPERTIES THAT AFFECT PERFORMANCE

Alloy Process Density Outlines Weight of Material

AI-356.2 Aluminum Cast 2.7 gm/cm3
AZ-91D Magnesium Cast 1.7
AL-6061-T6 Aluminum Forged 2.7
MA-14 Magnesium Forged 1.8

As you can see from the above the cast and forged magnesium produces the lightest wheel. Magnesium is 34% lighter than aluminum.

Alloy Process UTS: Ultimate Tensile Strength

Al-356-2 Aluminum Cast 228 mpa/33 KSI
AZ-91D Magnesium Cast 230 / 34
AL-6061-T6 Aluminum Forged 310 / 45
MA-14 Magnesium Forged 328 / 48

This is an area where the forged process gives you higher strength and performance. The higher the number the stronger the wheel. This means that the forged aluminum wheel is 36% stronger than the cast aluminum wheel. The forged magnesium wheel is 42% stronger than the cast magnesium wheel.

Alloy Process YTS: Yield Tensile Strength

Al-356-2 Aluminum Cast 166 MPA / 24.1 KSI
AZ-91D Magnesium Cast 160 / 23
AL-6061-T6 Aluminum Forged 276 / 40
MA-14 Magnesium Forged 287 / 42

Again, this shows the yield tensile strength of the product. You can see that the forged aluminum is 66% stronger than the cast aluminum. The forged magnesium is 79% stronger than the cast magnesium.

Alloy Process Elongation

Al-356-2 Aluminum Cast 3.5%
AZ-91D Magnesium Cast 3.0%
AL-6061-T6 Aluminum Forged 12.0%
MA-14 Magnesium Forged 10.0%

This shows how brittle the material is. The higher the percentage number the stronger the material is. The lower percentage shows that the material is more brittle and is more likely to fail under an impact.


Bruce

[JW]

Very nice info. When I built my 2" X 1/2" thick by 14" wide plate I used the AL-6061-T6 aluminum bar stock.