question on lift strakes

jprice · **Posted:** Fri Jul 13, 2012 7:06 am

I'm currently in the process of test fitting the lift strakes to my hull.
According to the plans, the chine strake fades out at about 3 feet short of the stem, and the inner strake ends at maybe 1 foot short of the stem.

The look fine so far, but when I look at pictures of various production boats, virtually all of them have the chine strake extend all the way to the stem. Usually the inner strakes extend to the stem (or very close) as well.
Is there any reason for this? Is there any performance benefit in having them run to the stem? Or is it just a style, visual thing at that point?

ucb4ume · **Posted:** Fri Jul 13, 2012 9:49 am

When I built my boat (not a Glen-L design) I didn't extend my lift strakes all the way to the stem as the plans called for. They only go about 3/4 the length of the hull. I just didn't like the way it looked.

The only reason I can think of why you might want to extend the strakes all the way forward is for strength in that section of the bow. When that part of the bow hits a wave at speed, the strakes would provide extra strength. With that said, I did not extend the strakes all the way forward and after 4 years for fast boating, I've never had a problem.

Here are some pictures of the hull before the turn over.

and a picture taken last weekend just for the fun of it

Iggy · **Posted:** Fri Jul 13, 2012 10:24 am

Wood boats are much lighter and don't take a lot of force to plane and will lift out the the water easily compared to the heavier plastic hulls.

I am thinking the expended strakes on those production boats help act as spray rails at the stem and probably little to do with performance (lifting) of the hull.

jprice · **Posted:** Fri Jul 13, 2012 10:44 am

Very nice boat ucb4ume.

In the 3rd picture, i notice there's a piece on the chine that runs full length. I'm guessing that's a spray rail, and not part of the lift strake?

Iggy · **Posted:** Fri Jul 13, 2012 1:13 pm

The piece on the chine is indeed the spray rail. I have the same thing on my Malahini.

Works pretty good for me so far.

ucb4ume · **Posted:** Fri Jul 13, 2012 2:09 pm

The reverse chine seen in the first three pictures does taper into a spray rail that goes all the way to the stem. The spray rail also covers the joint between the top side planking and the bottom planking.

This shot shows the outer chine log before the spray rail was installed

one more shot: giving rides at the Franklin, Louisiana Wooden Boat show

kens · **Posted:** Fri Jul 13, 2012 3:19 pm

There no reason for lift strakes to go way way forward, they serve to help the running bottom gain more speed by breaking up water friction under the hull.
With a hull up on plane and running, the bow is dry anyway.

jprice · **Posted:** Sat Jul 14, 2012 9:17 am

Thanks guys.

Of course answering one question is guaranteed to generate more. :lol:

Now I'm wondering if I need to add a full length spray rail?
The plans also refer to the lift strakes as a spray rail, although the chine strake ends about 4 1/2 feet from the stem. Will not having a strake/rail for that last 4 1/2 feet make a big difference?
I know it's something I could add after it's done, if it turns out to be a really wet ride, but I'd like to avoid doing that kind of work on the finished hull. On the flip side, I'm not sure I like the look of the full length rail.

ugh... decisions, decisions.

ucb4ume · **Posted:** Mon Jul 16, 2012 6:51 am

The spray rail will help to keep the boat and passenters dry when plowing through waves. In my case, it also covers the joint between the bottom planking and topside planking.

Bill Edmundson · **Posted:** Mon Jul 16, 2012 6:57 am

The forward sprayrail, above the waterline, helps at low speed in choppy water and when you are coming off of plane.

Bill

Iggy · **Posted:** Mon Jul 16, 2012 7:14 am

I opted to use a spray rail on mine. I like how it not only keeps the spray down but also protects the corners of my plywood edges from the odd bumps that happen during trailering. The only negative I've heard about spray rails (ouside of how it looks) was someone mentioning they could possibly 'catch' while turning hard sideways on a wave and possibly flip the boat. I believe the person mentioning it was talking about a smaller boat (squirt I think), so that might have something to do with it.

ttownshaw · **Posted:** Mon Jul 16, 2012 7:24 am

Here is a good shot showing exactly what Bill E. mentioned as I'm coming off plane.

Attachment:

malahini-shaw10.jpg [ 62.28 KiB | Viewed 511 times ]

ttownshaw · **Posted:** Mon Jul 16, 2012 7:40 am

Also, I have experienced the "trip chine" first hand. Not a fun experience at all! I'm ever aware now of the conditions that cause this and it's easy to avoid. Never, ever, ever, ever edge (parallel) into a wake/tide/roll at speed (on plane). In a few instances I have been stuck with not being able to change course so I drop off plane quickly and either take it broad side (if not too big) or nose into it with a quick course deviation (if bigger). Better to get a little wet with spray than causing other bigger problems.

Glen-L.com

question on lift strakes

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