What plan for tiller use?

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Fuzz
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What plan for tiller use?

Post by Fuzz »

I have a Mercury 50HP fourstroke with a tiller. I am wondering which plan would work with that motor and give me a hull that runs close to level and is easy to see over. I built an OD-18 but it wants to run so bow high I am blind ahead when sitting down and running it on step. I will be adding a center console and different motor to the OD-18.
Thanks, Fuzz

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Re: What plan for tiller use?

Post by jacquesmm »

The OD18, like all planing boats of that size, was designed to be used with a console, not tiller steering.
All planing boats -> ALL, will have a bad trim with one person sitting in the back.
You need either a tiller extension or a console.
A tiller extension works with some small boats like the FS12/14 or maximum FS17 if other weights are moved forward but never with an OD16 or 18.
You can't fight the laws of physics: the center of gravity must move forward.

Solutions: instead of building another boat, add a console to your OD18.
Which motor do you have on your OD18?
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Fuzz
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Re: What plan for tiller use?

Post by Fuzz »

Jacques,
Thanks for the reply. I had a 50HP 4-stroke merc on the OD-18. I have another one of the same motor that is set up for remote and will be putting it on the dory. We have a 50hp limit, and it must be 4-stroke, on much of the rivers I fish so the choice of power is a little limited. I understand about trimming the boat and that is why I had about 400lbs of people sitting forward of center.
I guess I have a case of boat building fever and can see myself starting another boat this winter. Some of the things I use a boat for tend to work better if you do not have a center console. That being said I was just wondering if you had a design that tended to run a little flatter. I thought it would be better to ask than to build one and see what happens :doh:
Thank you very much, Fuzz

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Cracker Larry
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Re: What plan for tiller use?

Post by Cracker Larry »

Fuzz, have you tried any kind of hydrofoil fin on you engine? It really helped to level mine out and gave me a lot more trim control.
Completed GF12 X 2, GF16, OD18, FS18, GF5, GF18, CL6
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Fuzz
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Re: What plan for tiller use?

Post by Fuzz »

Thanks Larry,
The idea of a foal had not occurred to me. I have never run one a boat but I have talked with others who liked them. I may give that a try before I do something else. I think Jacques is right and my best move would be to put a center console in the dory.
I was hoping to save my remote controlled motor to put on a 20 Panga. I have no need for a Panga but I love the looks of them. I sort of planned to tell myself that I had the unused engine just sitting around so I might as well build a boat for it :lol: At least that is what I was going to try on the BOSS, not real sure she would have fallen for it though :doh:
Fuzz

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Re: What plan for tiller use?

Post by cottontop »

Fuzz, Glad to see you got her finished. I have a 50-4stroke Merc on mine. I had to add a fin to my motor too. She would tend to porpoise quite a bit. I just got through doing a little remodeling (added a bilge area/back was open before), repainting the inside a light grey (not as hard on my eyes as the Orcas White was), and a jackplate. I'm in the process of retuning her now. You might look at the "smart tabs". If I don't like the way she trims up when I get her "retuned", I may order a set of those. Jacques and Larry are right when they say you should add the center console. This boat does need some weight forward. John

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Re: What plan for tiller use?

Post by jacquesmm »

Fuzz wrote: . . . That being said I was just wondering if you had a design that tended to run a little flatter. I thought it would be better to ask than to build one and see what happens
Such a design would go again the laws of physics.
To plane means to lift the hull partially out of the water. This is done by pressure on the bottom. At a given speed, you need a certain area to lift a given weight. That lifting area has a center and if that center is not under the center of gravity, the trim will be bad.
That is what you experience.
You ask me to move the center of lift, I ask instead to move the center of gravity by using a console.
There is no way to move that center of lift in a "normal" boat.
The only exception is a 3 point hydroplane.
In a vee hull or flat bottom, I would have to put the center of lift between the tiller man and the engine. Can you imagine the shape of such a boat? It's not possible, sorry.

About that center of lift, do not disregard the recommendations for a fin on the outboard plate like a Doelfin. What the foil does is to add lifting area as far aft as possible. That moves the center of lift back. Large trim tabs angled down will produce the same result but also produce drag.
It is much easier and technically far better to move weight forward but if you insist, Doelfins will limit the damage.
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Fuzz
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Re: What plan for tiller use?

Post by Fuzz »

Thanks to Jacques, Larry and John,
It looks like the voice of experience and wisdom from having already done that have spoken. I will listen and install a center console. It is the end of our boating season so I have all winter to get it done. I am pleased I tried it out and now have plenty of time to make the change. I will also keep the dolefin in mind if it turns out to be needed. One last question, I hope, I read where some folks are placing there console a little more forward than what is shown in the plans. Does anyone know how this turned out
Thanks again, Fuzz?

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Re: What plan for tiller use?

Post by Cracker Larry »

Mine is about 6" forward of the plans, plus I have a 40 gallon tank under the bow deck. This boat likes some weight forward.
Completed GF12 X 2, GF16, OD18, FS18, GF5, GF18, CL6
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Re: What plan for tiller use?

Post by jacquesmm »

I confirm what Larry said: the console can be further forward.
When calculating the LCG (= console location), I counted on one man at the wheel and another one next to the console, one battery in the back, ground tackle and tank in the bow. Most of the time, you will have a second battery in the stern and the crew standing behind the console. Therefore, move the console 6" forward.
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