What about the 25" Motor ?

[cadeco]

I have read many posts from people tha had brackets installed on the Seacrafts, many times they say that they had to raise the motors (they were using 25" motors) in order to run perfect. Why can't a 20" motor be used instead of the 25" to solve this issue, one aspect of it would be cost since looks to me that 20" are cheaper then their 25" counterparts. Can someone clarify it to mew? Thanks

[Old'sCool]

My '23 w Hermco required a 30" for single or 25" for twins

[cadeco]

That's another question: Why it happens?

I guess that installing a bracket is something like " Do whatever you want!" and latter find out how to deal w/ it.

Yes as i said before i have seen a couple of posts from guys saying that they had to raise the motor a lot and in some of those posts even going to the last bolt, they feel that it should go up even more. That's why i asked the question: 20" shafts are ( in comparison) cheaper then 25" and so, why not?

[flyingfrizzle]

Originally Posted by cadeco

That's another question: Why it happens?

I guess that installing a bracket is something like " Do whatever you want!" and latter find out how to deal w/ it.

Yes as i said before i have seen a couple of posts from guys saying that they had to raise the motor a lot and in some of those posts even going to the last bolt, they feel that it should go up even more. That's why i asked the question: 20" shafts are ( in comparison) cheaper then 25" and so, why not?

On a 20' hull you can get by with a 20" motor but it will make the power head closer to the water than most people like. THe 25" motor will almost have the tilt/trim motor out of the water at rest where the 20" motor at rest will be down fairly far. The biggest problem I have seen is when you back the boat down. With the heavy rear weighted bracket the water swamps the outboard more with a bracket and the higher you can keep it the less issues of water intrusion. I wouldn't even try it on a 23' hull but you may get by with a 20' hull if you keep the boat calm water with a super light outboard. The taller leg just makes more since...

[Bigshrimpin]

Originally Posted by cadeco

I have read many posts from people tha had brackets installed on the Seacrafts, many times they say that they had to raise the motors (they were using 25" motors) in order to run perfect. Why can't a 20" motor be used instead of the 25" to solve this issue . . . Can someone clarify it to mew? Thanks

You can with some brackets . . . but it depends on the dimensions. For example if the depth of the bracket is 25" (designed for 30" motors) and you mount a single 20" shaft outboard on the bracket . . . you'll just make margaritas. Follow?

[gofastsandman]

Originally Posted by Bigshrimpin

You can with some brackets . . . but it depends on the dimensions. For example if the depth of the bracket is 25" (designed for 30" motors) and you mount a single 20" shaft outboard on the bracket . . . you'll just make margaritas. Follow?

Where oh where is my Spidercrab, where Oh where can he be.?

[Bushwacker]

Originally Posted by cadeco

I have read many posts from people tha had brackets installed on the Seacrafts, many times they say that they had to raise the motors (they were using 25" motors) in order to run perfect. Why can't a 20" motor be used instead of the 25" to solve this issue, one aspect of it would be cost since looks to me that 20" are cheaper then their 25" counterparts. Can someone clarify it to mew? Thanks

I understand where you're coming from, but I've put some numbers together based on my own rig, and I can't say for sure that a 20" motor would work. Depends on the specific bracket design, how low it's mounted on the boat, and what sort of prop you run. All I know for sure is that mine works fine with AV plate 3.5" above keel. How well it would work at 5 or 5.5 inches, I frankly don't know, although I intend to eventually try mine at 4.5-5". Frizz, how high did you end up mounting the motor on your 20' Sceptre and what is setback on that bracket? Besides the powerhead-close-to-water issue, Frizz also made a good point about how close the Trim & Tilt system will be to the waterline. If you left the boat in saltwater all the time, I think you could expect potential corrosion issues on those parts. When comparing motors I'd recommend adding the cost of a Bay Mfg. motor extension to the price of any 20" motor, just it case it didn't work!

Here's a summary of the measurements I made using the setup pictured below, where I carefully trimmed motor to make sure AV plate was parallel to keel. Last set of numbers in each row is what height would be on a 20" motor:

Bolt location / Mounting hole / 25" Av Plt Ht / 20"Av Plt Ht
OEM + 1" / # 4 / 3.5" / 8.5"
OEM / # 4 / 2.5" / 7.5"
OEM / # 1 / 0.5" / 5.5"

OK, here's the code to interpret cryptic table above. (Sorry the "columns" don't line up but didn't have time to make separate table!):
OEM = motor mounting bolt holes located where Don Herman originally drilled them. He later redrilled the holes at a 1" higher location, which is indicated by OEM + 1".
Mounting Hole #: Top hole in motor bracket is #1, bottom hole is #4. Distance between holes is ~11/16"; total distance from top to bottom hole is 2".

I don't have any good photos of my AV plate at cruise . . . need to put some black tape on it because it's hard to distinguish the white motor from white water, but it looks like AV plate still needs to come up another 1-1.5" so that would put it at 4.5-5". Don and I have discussed bracket mods required to do that but it won't happen for at least another couple months.

With regard to a 20" motor . . . my measurements indicate that if it was mounted as low as possible on my boat, the AV plate would be 5.5" above keel and I think that MIGHT be 0.5 -1.0" too high, depending on what prop you run. Will know better after I raise mine and test it. I need a stern lifting 4B prop; the PowerTech ELE4, the BRP Cyclone and Michigan Apollo 4B props all seem to grip pretty well and may be able to run higher. Dixon said he could run a 3B Stilletto prop very high on his transom mounted motor, but it might not generate the stern lift you'll generally need to counteract the CG shift created by a bracket on a 20.

All of the above numbers are for a 25" E-TEC on a Hermco bracket with a 30" setback. I don't know if all brands of motors use common standard dimensions but it would be worth measuring hole spacing to be sure. Don mounted the bracket per his recommendations; swim platform height is about 2" above water at rest and just touches the water when a couple of big guys standing on it, so bracket height is perfect and I wouldn't want to change it.

Now I have to admit that I didn't see much of a performance increase with the last 1" raise of the motor . . . maybe 50 rpm and 1 mph . . . so maybe it's not all that critical at the 20-25 kts I typically cruise at, but all the experts on both the E-TEC and Verado forums say that the AV plate is designed to run on top of solid water, so you've got extra drag if it's deeper than that. Plus all the years I spent trying to tweak jet engines to get the last 0.1% improvement in thrust and/or fuel consumption has made me a fanatic at trying to get the most out of an engine, so it kinda bugs me to know there is a potential improvement I'm missing!

[Terry England]

- And that is why Denny is the "Leader of the (Preformance) Pack"
(He's got so much inside his head it pushed all his hair follicles out just to make room!)

[hermco]

Originally Posted by Terry England

- And that is why Denny is the "Leader of the (Preformance) Pack"
(He's got so much inside his head it pushed all his hair follicles out just to make room!)

[flyingfrizzle]

Originally Posted by Bushwacker

Frizz, how high did you end up mounting the motor on your 20' Sceptre and what is setback on that bracket?

The bracket has a 22" swim platform with the motor mount tab offset outwards behind that for a full 23.5" of set back.
I have been as high as 5" up from the keel and could run at that with a rev four prop as long as I didn't trim it up to far. The mirage didn't like that height. The best all around setting seemed to be 4" up. I went as low as 3.5" and back up to 4". I could run 4.5" with a clever or surface prop but for every day use 3.5-4" for max performance and handling. If offshore I would stop at 3.5" but if you run the back creeks or rivers like I do in my 20' then you can get that extra 1/2" and pick up a little more speed. Even at 3.5" there is a lot of spray off of my av plate. It is not under but not running clean either. I haven't ran it yet with the light new motor so that may change everything. All these test were with the 435lbs 225 mercury 3.0 2 stroke. The 2.5 I have is a little under 400 lbs and should help the balance some plus I still don't have gas in the hull yet. I have ran off of 2 6 gallon pony tanks at the rear. Gas weight forward may change things a lot too. I haven't got 2 hrs on the hull so I haven't ran it enough to really be sure how it will do in real world conditions, I have just been running it up creek a mile or 3 and back down to the ramp.

cadeco:
If you tried to do a 20" shaft on a bracket you probably wont find one that will work that is a production model. You could build one or set one super low on the transom maybe like an inch up from the keel and get the mounting tab low enough maybe but at rest you will see that the swim platform will be at the water line almost. Your hydraulic steering will be the only thing above the water on the outboard mounting clamp. The mounting tab will have to be super short and the 4 mounting bolts will be under the swim platform or the top two will be an issue with clearing the swim platform where they need to be drilled at. With a 25" leg the bottom 2 mounting bolts are high as they can be on mine to get the 5" of motor height with my platform 2-3 inches off the water. There are so many different variables it will be different from bracket to bracket due to the way they are made. Also there are a lot of things that can fowl the install up if you don't take good measurements prior to making your own. Not only dose the top of the swim platform need to be above the water you don't want it to high. You can only go so low with the flotation tub to allow the water to cleanly exit the hull bottom with out spraying off the tub and dragging you down. The tub height has to be dead on and work well with a chosen mounting heigth. The motor mount tab has to be figured in to that so the mounting bolts will clear the platform or tub top plus at the same time it has to have the correct av plate mount height. All of these need to work together so there is little room for error. What I am getting at is buying a random bracket and hoping it will work on you hull is not as easy as you may think. Not only that but it needs to have the right degree lay back to match the transom angle. Hermco has done a good job getting the dimensions right so it will work well on these hulls. I would go that route or get one built to the seacraft hull spec so everything will work out right. You may get luck and find on that fits well or find one that can be modified to fit but pay attention to the details or your boat will not be happy.