Glen-L.com

I am about to begin cutting the holes in bottom of my boat that I am building, for the prop and the shaft. Don't want to make a mistake. Any advice on choosing the correct spot and the correct angle and are the Glen L plans accurate according to the plans as far as placement.

Appreciate any advice,

Robert

Hi Robert.

Please remind us what you are building.

The angle of the shaft hole must be matched to your shaft log, strut, and engine location.

I recommend doing a full-size mock-up drawing so you can see where everything will end up. I have attached a couple of pictures to illustrate.

If you follow the link in my sig line, you'll find my build blog for my Monaco. I tried to keep decent photos of the shaft bore.

Good luck.

_________________
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project

Here is a thread for this:
viewtopic.php?f=2&t=8656&start=0&hilit=drilling+shaft+hole

Bruce said.
The angle of the shaft hole must be matched to your shaft log, strut, and engine location.
I prefer to think of it as :
'the shaft angle is determined by the strut'

_________________
God Bless our Troops; especially our Snipers

The answer to the question is that the strut location determines all the other parameters including engine position. The strut location can vary only a little because of frame interference and rudder post placement. In my Monaco, I needed enough clearance between the rear of the strut and the forward edge of the rudder for the prop and (room to install and remove it) and the shaft end with nuts, cotter hole, etc. Dave Lott in his usual thorough and careful way has written a piece on this whole issue. The strut position is limited in forward position by frame 1 in the Monaco/Riviera because the backing plate can only sit against the frame and not more forward. There you have the position decided: forward enough to leave room for the prop and aft enough to clear the frame.

I set mine up with the backing plate forward end against the frame. Incidentally, that is how the Monaco design drawings show it. We will see if I am right or wrong when engine install time comes around.

I lined the shaft hole, the rudder port hole and the water intake hole with fiberglass exhaust tubing segments. The stuff is made by Centek and comes in sizes that step by the quarter inch. I bored a 2" shaft hole and lined it with 2" exhaust tubing with an i.d. of 1 3/4". The rudder port called for 1 1/2" i.d. and I used 1 3/4" o.d. tubing. Epoxied in place this tubing makes a neat and substantial barrier to water access to the substance of keel and hull. This is a lot easier than trying to roll fiberglass cloth around a mandrel and stuff the hole with wet epoxy and the roll. There is the added virtue of a secondary moisture barrier to the bedding compound as sealant at the rudder port and water intake holes.

The "Princess" is coming along. Her namesake's wedding day is less than six weeks away.

_________________
Bill

Built a Monaco named: Princess

Thanks for all the responses. I did fail to mention that I am building the Glen-L Gentry. Another question that I have: Is it easier to drill the holes before you put on the decking?
Thanks again,
Robert

I drilled all my holes while the hull was upside down. I would think it would be much easier while the boat is upside down and before the deck is on.

_________________
John Amundsen
Monte Carlo
Winter Haven, FL

Maybe it will be done by G6 and maybe not.

Robert.

Did you mean planking or decking?

Generally, we bore the shaft hole after the hull is planked. But before we flip it and put the deck on.

_________________
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project

As everyone has stated the strut will dictate the placement of everything else.

So let me give you some measurements about its placement. Ideally the prop should be as close the rudder as possible. However, practically you need 4-6" of clearance between the trailing edge of the prop and forward edge of rudder. Balance that measurement with the need to have the strut not under a frame member .

Get the front to back measurement on your rudder. If you align the trailing edge of your rudder with your transom, mark where your front edge will be. That becomes point A.

Mark 4" up the keel from Point A. This becomes point B and is the maximum point your trailing edge of your prop should be. You need this much clearance between your prop and rudder in order to get your prop off without having to remove your rudder.

Ok, give yourself an 1" for your prop nut, meaure your prop collar (say 3") and then give yourself another 1" clearance between your prop color and the trailing edge of your strut. This number should be around 5". Mark this point further up the keel. This becomes point C and the furthest aft your should place your strut. Now you have a starting point to place your strut.

From point C you will be able to place your strut and see how it lines up with your frame. You should have a few inches of wiggle room forward before a frame member will mess you up. If you are using a new crate engine you might want to move your strut so that you bumping up to the frame with its backing plate. Reason: center of balance. The new engines weigh more that their older reliable classics. What ever you do: DO NOT move your strut in front of your aft frame member. There is one horror story on this board with a gent who did that. His weight was so far forward he could not get on plane.


Don't go much further than 6" from your rudder so that you don't have the potential of your prop wash missing your rudder and you lose steering control.

A big suggestion. Offset your rudder on the centerline of your boat by an inch. This will not affect your steering but will let you remove your shaft without pulling your rudder. I failed to do this and recently had to remove my shaft to repair a leak that developed in the shaft hole. I literally had to remove the strut to get the shaft out. Don't give yourself brain damage on this. Move the rudder center of alignment to one side by an inch.

If you want to see the mathematic layout on all of this with diagrams, go to my website. On the left is a link to the shaft hole boring.

Good luck. It is far more intimidating that it really is.

dave

_________________
Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.

I worried over this for weeks and in the end it was a no brainer. Follow Daves instructions and you will be just fine. I dont remember if you said you had the Glen L book on engine installation. If not you should get it as it is a wealth of info.

_________________
John Amundsen
Monte Carlo
Winter Haven, FL

Maybe it will be done by G6 and maybe not.

Not to hijack, but this raises a question on mine. Twin screw and single rudder work, or need two rudders?

Thanks, Chris