TW28 Questions for Jacques

[Jeff]

This question just arrived via email: "Hi there, I have been looking around for awhile for a boat build project and have come across your TW28 and have to say I do like the lines. Like the box keel a lot and the fact its stitch and glue as well. I live in Victoria Australia, with the thought of on day; taking a trip across the ditch to NZ in my own boat. It's a 1250nm trip and can get rough lol the dirty little Tasman sea. Would this design by ok for this. Or do you have a slightly larger design along the same lines. Look forward to hear from you. Regards Ted" Jeff

[jacquesmm]

No larger version at this time but some builders have scaled up the TW28. It is easy to do in metric, 10% up is a good and safe way to scale.

As for the behavior at sea, the TW28 will behave like all trawler boats of that size, a little better in my opinion.
For long distance, you could add a stay sail and paravanes.
I would go for paravanes.

[Tritonute]

Hi Jacques
Thank you for your reply
If I am to lengthen the TW28 by 10% to 31ft do I add 10% to the beam as well ??
Plus would I still use 50 hp as a standard engine size, but would be able to add extra tankage for fuel.
Thank you for having this forum as I believe it is a great thing to have.
Ted

[jacquesmm]

You would scale all the dimensions by 10%. That is easy and correct.
You will automatically have larger fuel tanks.
You can also install a larger engine but a 50 HP will move the larger hull without problems.
Those 4 cylinders natural go up to 80 HP in different brands.

[Tritonute]

Hi Jeff,
Thank you for the reply.
One question can you add 10% to the 10%. Just a thought.
As would love a boat of approx 35-36ft.
Ted

[fallguy1000]

After some point, the scantlings and laminate schedule fall out of design safety factors.

If a designer designs a boat with a safety margin in the hull thickness, bulkhead spacings, and glass schedule, at some point in a length a/o beam increase, the boat falls out of spec.

Adding to a boat's dimension is not arbitrary.

[jacquesmm]

Correct. Scaling by 10% is the maximum I recommend.

[Peekhomer]

Ok, here is my question. I have a saw mill and access to white oak for frames and planking. Is there any reason why I cannot put a solid keel under the TW28, steam frames and Carvel plank the hull?

[TomW1]

Ok, here is my question. I have a saw mill and access to white oak for frames and planking. Is there any reason why I cannot put a solid keel under the TW28, steam frames and Carvel plank the hull?

You are no longer building a stitch and glue boat and loosing the advantages of doing so. It will weigh many times more than the design weight of TW28. Every thing will be need to be redesigned. Stringer and frame placement, etc.

Tom

[jacquesmm]

Correct. This is not a wooden boat. There are no fasteners, the box keel is part of the hull. Even if it was, the keel is a hollow box keel.