LB26

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Fuzz
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Re: LB26

Post by Fuzz »

From the pictures things look pretty good to me. Is the problem you do not have enough height from the shaft to line up with the engine? If so making the shaft longer and moving the engine a little forward will make things taller. As I am not sure of the problem I am only guessing. Please let JM give you the answer and not one of us who are just guessing.

jacquesmm
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Re: LB26

Post by jacquesmm »

I am guessing too Fuzz.
Let's wait for les reply, he is 7 hours behind of me and 11 for you.
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fallguy1000
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Re: LB26

Post by fallguy1000 »

jacquesmm wrote: Tue Apr 12, 2022 4:17 pm
les2021 wrote: Tue Apr 12, 2022 11:13 am Questions

My engine stringers are spaced further apart to accommodate the engine, so if I then leave 300mm to the outer stringers it means that between frames C and D my stringer height if I keep them 12mm below DWL are only about 60-70mm . Is this ok or can I raise them up above the DWL to get more depth if needed.
The stringers height is set by the engine mounts, you don't have a choice. The width is set by the mounts also but on a L bracket bolted through those stringers. From the engine drawing, I see enough clearance between the mounts, nothing sticks out.
Can you post the engine drawing as a downloadable file?
Sorry but I do not see where the problem is, it looks fine to me.
Les-you and me are a lot alike. Sometimes too precise...it can be good.

I am going to stay out unless I can add value.

For this type of question; you need to offer a sketch because it is so hard sometimes to comprehend. Even a hand sketch no ruler and a picture on paper makes it easier for anyone.

I assume you mean engine stringers, and I think I understand the question.

Moving the engine forward 4" might require longer engine stringers which would mean they are a wee bit lower heightwise forward as the hull rises to the bow. They are only offering a home for the engine supports. I believe you are worried they are structurally deficient due to the lower height forward. This is not the case. They get their strength from tabbing and 60mm is 2"+ and the tabbing should be fine as specified.

All the best. I will try to stay out unless I can help the designer interpret a question.
My boat build is here -------->

viewtopic.php?f=12&t=62495

les2021
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Re: LB26

Post by les2021 »

After Guys

Jacques / Dan / Fuzz

Dan I will take that last post as a compliment :D

Ok sorry for not making my questions more clearer. I will break them down into individual topics.

1. Engine position and shaft log.

2. Outer stringers.

3. Knee laminating schedule.

4. Frame E ( new question )

1. If you look at my sketch below, if I cut the log off 75mm as it exits the hull this will allow room to clamp the bellows, from exiting the hull the shaft seal is 209mm I then have a gap to the coupling of about 125mm ( is this ok )
If so this will leave me approx 840mm to the cabin entrance / frame D.

2. As I have had to make the engine stringer space wider to accommodate the engine my outer stringers have moved up the hull. This means between frames C - D the stringer height will only be about 75mm ( is this ok ) drawing below...

3. You have confirmed mounting the two knee braces up against the inside of the inner stringers is fine. The other part of my question was laminating them, I can not see them on the schedule. ( My question was do they come under the superstructure or stringers and floor frame schedule. )

4. Frame E shows the floor frame part of the frame going under the engine ? If this is so it cuts off access to the drip tray sump etc. It looks like you have about 230mm of frame is there a minimum incase I can not achieve that ?

Dan sorry for the confusion. The engine stringers have turned out really well and all is ok in that section.

You are right though from years and years of looking at and reading drawings if I see a measurement I try to keep to it. Looks like I need to relax a bit !!!!

Once again cheers for all the patience and help guys.

Les
E3E71C94-D5EC-4A3B-B5EE-39977628B9B3.jpeg
C63BFF64-15A9-410A-9687-DF0988F02422.jpeg

jacquesmm
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Re: LB26

Post by jacquesmm »

Thanks for the drawings.
Engine location first. Everything else will be decided based on engine location. You have no choice with the engine location.

Does the profile drawing show the engine location that you propose?
It looks good except for one item: the seal to coupling distance.
You should be able to remove the seal without pulling the engine and that means minimum 209 mm plus a small safety margin, let's say 250 mm.
This means that you should move that engine 125 mm forward of what you show, or more. You have the room in the front.
To move forward has advantages: the rear part of the stringer will be higher than the 75 mm you mention and there will be more clearance all around the engine.

Can you check that location first?
We will cover the other question after we decide about the engine location.
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les2021
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Re: LB26

Post by les2021 »

Afternoon Jacques

Thanks for the reply.

I am still a little confused.... The engine is in the position that I think works it has a good distance between the cabin entrance and a good clearance under the sump.

The bit that I am confused about is removing the seal without pulling the engine. My understanding is as follows

The bellows only goes over the stern tube by about 75mm, so to remove it I need to slide it forward 75mm, I have about 125mm to the coupling so removing the seal would be ok ( have I missed something ) If I have to moving the engine forward another 50 -100mm it would be ok but I do not want to cramp the entrance to the cabin.

The 75mm stringer question is on the outer stringer not the engine stringer.

Once again thanks for your patience on this one.

Cheers

Les

jacquesmm
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Re: LB26

Post by jacquesmm »

The distance between the engine coupling and the end of the fiberglass tube must be longer than the length of the compressed shaft seal.
If you can take that shaft seal out in several pieces, that distance has to to be longer than the longest piece. Give it a couple cm for safety.
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Fuzz
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Re: LB26

Post by Fuzz »

You will also need room to install the shaft coupling unless you plan on installing it before you set the engine. Sooner or later you will need to work on the shaft seal and you do not want to have to move the engine forward to have room to pull the coupling and reinstall it. Getting a shaft coupling off can turn into a major fight! Been there and done that :help:

jacquesmm
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Re: LB26

Post by jacquesmm »

Yes to what Fuzz says. I assumed that the shaft seal can be compressed enough to pull the coupling but that is not always the case. Include the length of the coupling in that distance.
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les2021
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Re: LB26

Post by les2021 »

Hi Guys

Once again thanks for the input Jacques / Fuzz.

Ok I think I am all clued up regarding the engine / shaft seal / coupling issue. I have ordered the seal so I can have a good look and make sure all is ok.

If necessary I will move the engine forward a little. The main thing Jacques is that you are happy with the engine position weight wise ?

Can you come back to me on the other questions.

Cheers

Les

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