MacGregorSailors.com

The owners manual says that you should have the rudders up if going over 5 MPH. I've tried and have a hard time maintaining a heading, it maybe because I have a 30 hp engine but I'm not sure.

Yes. Macs are like that. It's not you.

You'll snap your rudders, or risk it, and/or cause a dangerous situation to your crew if you keep the rudders down over those speeds.

30 hp is nothing.

Driving takes time and experience - turn it much much much less than you think you need to. Wait. Adjust more if needed.

I'm shure you can use your rudders down at speed up the mac will go to planning. And this is till 6kn. You also sail at these speeds.

Above that that mac goes towards planning. And then the rudders must go up. But with 30HP this will not happen I guess.

What is your speed you want to motor?

I keep only one of them down when motoring without the mast, but that's with ballast in and not over about 6 kts. But my doesn't seem to wander around at higher speeds, at least with the ballast vent and valve open while I'm draining ballast. At low speeds with no rudder(s), it's all over the place.

With the 30hp it will do 9.5 mph with the ballast in and about 13-14 with it empty, never planes though. It just will not hold a heading at all without at least one rudder down. My thought was maybe the lower unit is smaller on the 30hp than the intended 50-60hp that is intended to be there and doesn't act as a rudder enough. I have a hard time keeping it within 10 degrees of where I'm trying to keep it pointed. It's almost like my trying to drive through a chine walk on the Hydrostream I used to have, just a lot slower.

There is a "sweet?" Spot I've noticed where the M is like Mr Toad's wild ride. Slower and it's ok. Running on a plane is ok. It's definitely not just your boat. I've got a 60, so I either ease along or plane. You can definitely use the rudders at normal sailing speed, but not above. Some owners have bonded skegs to the hull to try and cure the problem. You might try to check w/RIS or Ixneigh.

See http://www.macgregorsailors.com/forum/v ... 72ce20b259

kurz wrote: ↑Mon Aug 12, 2019 1:00 am And this is till 6kn. You also sail at these speeds.

I don't have the skilz to know for sure, but I suspect there is a fundamental difference between sailing at 6 knots and motoring at 6 knots when it comes to forces involved.

i.e. just because it's OK to sail at 6 knots with the blades down doesn't mean it's OK to motor at 6 knots with the blades down.

But I have no evidence to back that intuition up.

(That being said, I still do use the blades when motoring at 6 knots - I'm just mindful that it might be risky on the hardware.)

I don't see the differens in motoring in 6kn and sailing in 6kn. I don't think motoring is heavier for the rudders.

I typicaly pull the rudders as soon as I clear the no wake zone leaving the marina. Ive forgotten a few times and the boat will remind you fast.
Cant explain the physics, but under power reacts different than under sail. Have sailed comfortably at 8mph but powering at that speed she gets very squirrely.

Good Day all, just bought a and getting it ready for first "sea trial".
And how about full power speed with rudders down on the ? Nothing in the manual and rudders are pinned down while in the water.

Macs are like that. Holding a beer doesn't help any

beechkingd wrote: ↑Sun Aug 11, 2019 6:26 pm The owners manual says that you should have the rudders up if going over 5 MPH. I've tried and have a hard time maintaining a heading, it maybe because I have a 30 hp engine but I'm not sure.

Prairiesailer wrote: ↑Sat Jun 12, 2021 6:10 am Good Day all, just bought a and getting it ready for first "sea trial".
And how about full power speed with rudders down on the ? Nothing in the manual and rudders are pinned down while in the water.

5.9 knots or 6.8 mph. Your boat will not plane. It is limited to hull speed.

beechkingd wrote: ↑Sun Aug 11, 2019 6:26 pm The owners manual says that you should have the rudders up if going over 5 MPH. I've tried and have a hard time maintaining a heading, it maybe because I have a 30 hp engine but I'm not sure.

There are two reasons why your rudders should be up when you are under power. They are related.

The first is that the rudders are a foil and are designed to work in conjunction with the sail and centerboard/swing keel. They exert forces that will turn the boat into the wind the faster the boat goes and they will effect the way the boat heels. Those forces are balanced or slightly tuned toward safely rounding up in a heavy wind while you are under sail. The faster you go the more these forces act on the boat.

When you are under power the same forces will come into play only you don't actually need them since you don't have the sails to work in conjunction with them. As you go faster these imbalances will get more noticeable and will affect your ability to steer properly.

The second is that if you go fast enough (basically much above hull speed) your rudders will experience more of these forces than they were designed to handle. Something will likely break or bend.

As far as maintaining a heading there are a couple of things to consider. The first is that our boats are harder to steer than others of the same size due to the high freeboard and the resultant extra windage. That takes time and practice to learn to get them to behave as well as they are capable of behaving.

The second was mentioned earlier and that is that they also get a little hard to handle during the transition between displacement and planing mode. It's best to try to get through that transition as quickly as possible.

And that brings me to the third point. A 30 HP engine may not be able to get you through that bad spot. At wide open throttle you may be sitting right on top of the worst handling speed you boat has. You have enough HP to get you into it but maybe not enough to get you past it.

The last one is a long shot but it may be worth checking. Your engine has a trim tab on the bottom of the foot, right behind the propeller. In most boats it is adjusted just a little to one side or the other of center (depends on which way your prop turns). If your trim tab is significantly off to one side or the other it may be affecting your steering. It's an easy check and and easy fix if it appears to be wrong.

At low speeds having one or both rudders in the water can make a world of difference to your ability to maintain course, particularly when the wind is hitting you from the side. The more you get above hull speed the more likely they are to fight you than to help you.

Be Free wrote: ↑Sat Jun 12, 2021 8:32 am

beechkingd wrote: ↑Sun Aug 11, 2019 6:26 pm The owners manual says that you should have the rudders up if going over 5 MPH. I've tried and have a hard time maintaining a heading, it maybe because I have a 30 hp engine but I'm not sure.

And that brings me to the third point. A 30 HP engine may not be able to get you through that bad spot. At wide open throttle you may be sitting right on top of the worst handling speed you boat has. You have enough HP to get you into it but maybe not enough to get you past it.

Your third thought is correct, that was from 2019. Now I have a 90hp, no more issues and with no ballast it will do 28 mph, 24 with it full and mast up.