Outboard motor placement

[Guest capt jake]

OK, to change the subject again, I recently acquired 2 outboard trolling motors and 1 electric. 2hp, 4hp and 23lb thrust.

Thh electric is probablay too small, so I will go withe the gas motor(s).

2 questions;

1 - 2 or 4 hp??

2 - Where to place the center line of the prop? I know Frank has touched on this in the past. I think these are both short shaft motors.

If you were to draw a line off of the hull bottom; (where in relationship to this line) would the center of the prop be situated? I am talking up and down, as to keep the prop in the water.

It is looking like the short shaft may be too 'short', to be able to control with the factory steering 'stick'. ?

Can the outboard and the rudder be combined into two (meaning, the steering of both at the same time)?

jwentz4@attbi.com

[Guest Frank Hagan, Weekender, O]

These small outboards won't really develop enough thrust to take over the steering. For instance, you shouldn't decide to let the rudder pop up as you are approaching the dock thinking that the motor will help you steer, as you could *THUNK* into the dock and make everyone there laugh hysterically. Don't ask me how I know.

So, you generally have them fixed to provide propulsion, and steer with the rudder. I think the 2hp would drive a Weekender at hull speed easily ... I have a 3.5 hp, which on these small guys is usually the same size motor with different labeling ... and it does fine. I have an adjustable bracket on mine now, so I can lower it or raise it (ebay, $22). Heartily recommended.

If you want to use the "tilt forward" feature of the outboard, you have a problem (especially with a short shaft). The cavitation plate ... that thing right above the prop ... needs to be several inches below the bottom of the boat. The Weekender only draws about 3", even with my 240# in the cockpit. That usually puts the motor itself below the top of the transom, so to tilt it forward you have to build a fixed mount with about 8" of space between where the motor mounts and the transom. I tried to compromise with my home built motor mount, and got the cavitation plate one inch below the bottom, which allowed me to use a lanyard to keep the motor tilted forward, but the motor cavitated a lot. If you go forward to dowse the jib, with your wife at the helm, she'll complain that you are pulling the motor out of the water and she can't keep it turned into the wind (this is usually prompted in response to your admonition to keep the boat pointed into the wind).

I'll have to look next time I'm out ... but I think the cavitation plate needs to be 4 - 5 inches below the water to avoid cavitation. That's several inches below the bottom of the boat.

fshagan@ev1.net

[Guest Ray Frechette jr]

I would likely go with the 4 HP myself if your going to sail in tidal waters.

If a short shaft motor, you need to get a motor mount bracket that raises up and down.

The stock plans wooden bracket only works with an electric, or a longshaft.

There is a flat metal platee on the mtor called a cavitation plate that needs to be just below the hull bottom.

When going forward on deck, as these boats are so small and so light, the motor is liikely to be pulled out of the water regardless what you do.

Steering is problematic as the motor and the rudder are quite close together. I am not sure how you could rig them to move them in tandem automatically, however you do need to move them together. Not so much for steering as to prevent the prop from chewing the rudder` ie:Motor trying to tur boat to starboard with rudder stucl in port turning position. This happened when my steering gear jammed in port turn position when rope slacked up. I was sailing straight at a dock and was trying to turn boat to starboard. Didn't work, and I chewed up the rudder.

I avoided dock by going a head with a hard port turn with the motor and rudder.

refent@prodigy.net

[Guest capt jake]

Thanks guys! I will be looking for an adjustable mount. Then I can try either motor.

Cavitation plate below the hull bottom by about 4-5"?

jwentz4@attbi.com

[Guest Ray Frechette jr]

I only keep my cav plate about 1-2 inches below .

Works for me unless I go up on deck.

Get that roller reefer engineered so I don't need to go up on deck.

refent@prodigy.net

[Guest capt jake]

jwentz4@attbi.com

[Guest Frank Hagan, Weekender, O]

Ray, I've found that if you have an adjustable motor mount, and raise the motor, the prop is then out of position to scar the rudder. While the motor is down, and under power, I keep the prop fixed and use the rudder to steer ... with some care, you won't hit the rudder with the prop.

I did mount my outboard bracket at the extreme port edge of the transom, and my little outboard is pushed all the way to port to give me the room I need. In this case, a smaller motor is better, of course.

fshagan@ev1.net

[Guest Graeme, SNUPI's builder]

Aaaahhhh !!!, I CAN'T TAKE IT ANYMORE ! I just HAVE to butt into this thread !

For what it's worth .........

I've run everything from 2 hp Evinrudes on 10' skiffs & canoes, 25' outboard Cape Islanders / 60hp Merc. to a 200 hp V-4 Evinrude on a 19' DURAL deep V / high bow,Blue Water planing / displacement hull rig, over the past 40 years !

A lot of my "stinkpot" boating was in the Atlantic off the coast of Nova Scotia .... There, you get it right or sink !

The rule of thumb, as used by every serious power boater / builder / O B Motor Dealer, I've ever talked to, is to place the motor's anticavitation plate at the same plane as the hull's bottom plane position to take advantage of a consistant water flow coming straight off the hull bottom, as much as possible.

The anticavitation plate prevents the propeller's blade tip's vertical turbulant wash from introducing air into propelled rearward moving water, thus reducing efficiency or "stalling" the propeller ! A poorly positioned prop will at the best create a a bunch of DRAG, ( too deep) or at it's worst,(too high),will suck air from the surface & create a "Cavity" of air in front and around prop blades and you'll get a motor running wild in this air/water mix, with no resultant "Push" !"

The vertical angle of the prop to the angle of hull to the water is also critical, affecting the hull's angle to the water surface but that'a a whole other subject, with trim plates entering the picture !

A few months ago & the BYYB, Terry C.responded rather rudely a my response to the correct O/B motor position on a sailboat with this argument,....

" WHEN THE SAILBOAT HEELS, THE PROP WOULD BE OUT OF THE WATER IF SET UP WITH THE ANTICAVITATION PLATE FLUSH WITH THE TRANSOM'S BOTTOM !!!"

I couldn't be bothered to respond to such an dumb statement, BUT, I gotta wonder .... "What the hell is he doing with the motor running and lowered in the water when obviously, HE'S UNDER SAIL !"

Unless his boat simply is so poorly built as to have a serious list, or the only other answer would have to be that he's what we call here in the East Coast,"A Weekend Motor Sailer" They sail downwind and motor upwind, with the sails still up and flapping in every imaginable manner !

There, I feel better now !

Graeme, Nova Scotia

graeme.realtor@ns.sympatico.ca

[Guest Ray Frechette jr]

The rule of thumb, as used by every serious power boater / builder / O B Motor Dealer, I've ever talked to, is to place the motor's anticavitation plate at the same plane as the hull's bottom plane position to take advantage of a consistant water flow coming straight off the hull bottom, as much as possible.

Agreed, however when I sail my Potter with the adjustble mount I generally aim for an inch or two below that point as it is a rough measurement when I drop the motor in and I wuld rather be deeper than to high.

Generlly I use my motor very little any way so extra drag under power is not much of a problem

refent@prodigy.net

[Guest Frank Hagan, Weekender, O]

I measured off the bottom to position the anticavitation plate originally, and found I had to lower it some more to prevent cavitation. That's on my little 3.5 hp GameFisher (Sears) outboard, which looks identical to the "Cruise and Carry" outboards. So maybe they haven't done a good job of locating the anticavitation plate? Or could rocker on the bottom of the Weekender cause a problem? Or perhaps because the Weekender barely settles into the water unless loaded down?

In any case, the use of an adjustable motor mount will allow the sailor to fix it at the right depth for whatever condition they have.

fshagan@ev1.net

[Guest Gordy Hill]

I try to position my oars so the blades are in the water. I've found that when I don't they tend to cavitate and I loose a lot of thrust.

sirgordy@peoplepc.com

[Guest Frank Hagan, Weekender, O]

fshagan@ev1.net

[Guest Graeme, SNUPI's builder]

Absolutely on the money, Frank !

I've learned that the trick when mounting a any motor for the first time on any hull, is to go with the "Normal Guidelines and ecperience", then FINE TUNE !

As you stated, the direction of the departure flow at the transom, varying from hull to hull, will certainly dictate the vertical positioning of the line of thrust and most efficient power.

Like anything,"Guidelines" get you 85% of the way down the correct course; fine tunning under actual use gets you another 10% of the way. The remaining 5% will consistantly elude you, either in actual fact or perception !

Once we understand the mysterious principles involved in any setup, fine tuning becomes second nature .

Graeme, nova Scotia

graeme.realtor@ns.sympatico.ca

[Guest T. Nelson Surbrook]

These are good points and once again a very good thread. I notice from your post that you took offence to Terry's nasty comments. This is why I am totally enjoying this board and never even look at the BYYB stuff anymore. Frank has put together a awesome board and the "RULE" is just right. This is one of my favorite places to visit on the web. Here you can have a good discussion on Ballast, radical modifications, and what some might call controversal subjects without someone getting nasty if they don't agree on some point. But what am I doing? I think I am preaching to the choir, you all know this already. This board RULES and the other one SUCKS. After all, what's better than just messing around in boats?

tnelson@surbrook.org

[Guest Graeme, SNUPI's builder]

Hi Nelson,

I couldn't agree with you more , Frank HAS DONE A TERRIFIC JOB ! And..... he's attracted pretty damn great bunch of helpful and friendly posters here, too !

KEEP UP THE WONDERFUL JOB, FRANK ! You've established a one of a kind builder's atmosphere here !

I found that 99% of the builders at the BYYB were likewise extremely helpful and in general a real good bunch to kid around with, get advice from and discuss various boat details and variations. Too bad somebody died and made one opinionated menber "RULING POLITICAL DICTATOR of ALL BOATING ~ BUILDER'S INFORMATION ! Rather overshadows one's thoughts when considering a post.

Sure turned me off !

If ever there was a boat with the doors wide open for some "picking on", it would have to be SNUPI ! I guess I pretty much strayed off the traditional Stevenson path, however not one post here at Mess-about" has taken up a good natured opportunity to comment on my "outer-space" ideas !

SHUCKS !

Now, gotta go back to my space ship's workshop !

Graeme, Nova Scotia

graeme.realtor@ns.sympatico.ca

[Guest Madmike8]

Hmmm.. I have a problem with this comment...

"This board RULES and the other one SUCKS."

Since a Board/Forum is really just a collective of people and their thoughts. This statement becomes "These People Rule and those People Suck."

I read both boards daily, and I think there are VERY NICE people on both boards. Why do some of the people on this forum feel that they must "compete" against the BYYB forum? BYYB has restricted itself to Stevenson Projects boats, and M-A has opened itself up to small boat building in general. BYYB is a group, and M-A is a gathering. Where is the competition in this? They are both execellent forums.

I'll give the folks of the BYYB this... I don't think I've ever read any post that makes a negative comment about M-A. I've seen them send folks to this forum when their questions could be better answered here, or when there was a good discussion going on over here.

On the subject of Terry's post... What helps me when dealing with his post is getting a mental image of "Mr. Wilson" from Dennis the Menace when reading his post...

In the words of someone...

"Why can't we collectively coexist."

Mike

P.S. to Frank..

These folks that have assembled here at M-A sure do make their appreciation for your work shown, and with good cause. Great Job.. Keep it up..

mmullins@vallnet.com

[Guest Johannah]

Graeme, get on along with all your "wild" ideas. I got days of fun, while driving around for work and family tasks, just thinking about your binnacle. Same kind of fun from pondering the builder who is working on a schooner rig. Considering these ideas and thinking over sailing stories or plywood discussions has added a lot to my life.

nanjojo@earthlink.net

[Guest Graeme, SNUPI's builder]

Hey Gal,

You'll see the infamous "Binnacle" before very long. Been busy doin' the "Real Estator" thang fer thet thar Century 21 crew, an' (TOP SECRET CLASSIFIED OPERATIONS) sailing 2" x 12" x 6' homemade "skateboards" with scale gaff / bermuda/ winged sails in school parking lots all summer! Ended up with a rotating airfoil mast with a modified full battened "semi-gaffless" gaff sail that looks, at first glance, for all the world like a battened/roached Bermuda ! In scale it outperforms 'em all for light wind and high pointing ! I used 12 sq.ft. sail area in all cases.

Paul has the preliminary scaled drawings, I've started drafting a complete set of detailed plans for him to work out a price for me.

Ive got updated pics, just have not taken the time to figure out the process for posting yet.

I'll send you a copy of the updated SNUPI from the next earth orbit.

Graeme

graeme.realtor@ns.sympatico.ca

[Guest T. Nelson Surbrook]

Madmike, It was only a joking comment about the BYYB sucking. Don't take me to seriously and we will be ok. My perspective may be differant from your's as I was a charter member of the BYYB and watched what could have been a wonderful orginization become something quite differant. While some of the people that use the BYYB are fine folks, some of those who run it may not be. My boat is built and I have been sailing it for 2 years now and maybe I have grown to the point that the other board is of no value to me. I could make some comment about nazis now but I won't. I for one find a one "rule" bbs far more to my liking. As far as compeating with the BYYB it was never about that. They are totally differant forums with very little in common. Over there people pay to belong to a "club" and here we go sailing. If you want to visit both bbs's, who cares? Here's the bottom line, I don't have to imagine the posters here as cartoon charactors to read their messages.

Shalom,

Nelson

tnelson@surbrook.org