Bunks on Alum boats with hull strakes -Where to place bunks?

Trailer related issues and discussion goes here.
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Tin Man
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Tin Man » 18 Apr 2018, 21:35

Hello all--

I'm back in the tinny world! I was going to purchase a 20'-22" Pontoon boat and decided that a small alum boat was more practical, economical, and a fun project. I believe the smaller the boat the more prone we are to use it!

I have a great lake in my city that has great LMB and Striper fishing. Excited about using my new boat out there and slaying some fish! Also excited about the many projects I can apply to my boat....many of which I have seen here on this board!!

Picked up a 2009 Bayrunner 15 last week! Excited about the simplistic approach to fishing/boating and the projects that can be accomplished on a small alum boat.

Trailer set up question....

My Bayrunner has strakes on bottom of hull that are spaced at 2.5" apart. This space does not allow for a carpeted 2"x4" to fit between them. On a previous alum boat, the owners manual stated not to place bunks boards under strakes; ensure they were between them. On that particular boat the strakes had more distance between them, allowing for 2x4 placement between them. I'm assuming the same applies here.

So, what options do I have?

Rip 2x4 down to a 2X2?
Use 2x4 on its ends (would require a different mounting bracket)?

Thoughts?
2006 Tracker Pro Guide V16 WT
2005 Mercury 60hp 4 stroke, EFI, 20" shaft
2006 Trailstar Trailer

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Scott F
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Scott F » 18 Apr 2018, 22:42

Turn the 2x4 on it's edge so the narrow edge is between the strakes.

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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 18 Apr 2018, 23:06

Yep, plenty of tinnys have the 2x4's on end.
Yes, you probably will have to buy different brackets, or modify the ones that you have.

I never did it, but imagine you could simply cut 2 extra pieces of 2x2s; screw them onto the lowest side of the upright present 2x4, and use the brackets that you already have.

(I haven't given this idea all that much thought, but it would be worth thinking further about and playing with on your own boat.)

https://www.etrailer.com/Boat-Trailer-P ... 0603G.html

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Tin Man
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Tin Man » 18 Apr 2018, 23:39

I'm a little concerned about the smaller footprint the 2x4 on its side gives.
I much prefer a wider footprint to spread the load...especially on the pothole-riddled roads in my town!!!

Do any of you run your bunks in a different manner or used a different solution?
2006 Tracker Pro Guide V16 WT
2005 Mercury 60hp 4 stroke, EFI, 20" shaft
2006 Trailstar Trailer

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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 19 Apr 2018, 09:09

The most you are going to get is the 2.5 inches that your strakes allow.

Turn your 2x4 on its side...then add a 1x4 on the side. The 2 inch is really 1.5 inches. The 1 inch is really 3/4 of an inch. Your result will be 2.25 inches of wood.

If you top it with thin carpet, you will just make your 2.5 inches. If the carpet is thicker, then you will have to rip ( or have someone rip) the 1x4 to a thinner dimension.

Alternatively, you could use a router and trim a small diagonal portion off of the top of your new bunks, tapering them to accommodate the carpet. It all depends on your woodworking tools and skills.

One used boat that I bought came with upright 2x4 bunks. I was able to turn them flat. But, it was fiberglass and had a very flat bottom.

regards,

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Tin Man
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Tin Man » 19 Apr 2018, 09:59

I like the idea of adding the 1x4 to the side of the 2x4. It may just work.

How would you attach the 1x4 to the 2x4?

What about ripping a 2x4 down to the 2.5" needed? This would allow the wood to flex to contour of the hull easier than a 2x4 on its side. It may also allow me to use the current bunk brackets I have now.

Need to verify if the bunk bracket will fit the 2.5" wood. Mounting holes (which attach with #14 hex head wood self-taping screws) of the bracket are about 2" on center which may be too close to end of wood...splitting wood on insertion.
2006 Tracker Pro Guide V16 WT
2005 Mercury 60hp 4 stroke, EFI, 20" shaft
2006 Trailstar Trailer

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LDUBS
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by LDUBS » 19 Apr 2018, 11:01

Tin Man wrote:I like the idea of adding the 1x4 to the side of the 2x4. It may just work.

How would you attach the 1x4 to the 2x4?

What about ripping a 2x4 down to the 2.5" needed? This would allow the wood to flex to contour of the hull easier than a 2x4 on its side. It may also allow me to use the current bunk brackets I have now.

Need to verify if the bunk bracket will fit the 2.5" wood. Mounting holes (which attach with #14 hex head wood self-taping screws) of the bracket are about 2" on center which may be too close to end of wood...splitting wood on insertion.
If you have bunk/bolster brackets that work like the one shown below, then adding a 1x4 to the side will result in your edge-wise bunks being off center to the bracket. No matter how much you tighten them, they would be constantly wanting to twist, which would be a real PITA and not good for your boat. In fact, even if perfectly centered using edge-wise bunks with this kind of bracket is probably not a good idea. You can replace the swivel part of the brackets with ones made for vertical bunks, but that would probably cost more than just replacing the whole bracket with the correct style (like in Rich's link).
Bunk bracket.png
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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 19 Apr 2018, 13:06

There is nothing wrong with ripping the 2x4 to whatever width you want, and whatever width will fit both the brackets and/or the strake opening. If you want more flex, then that is the way to go.

I am not sure that I understand ...."Need to verify if the bunk bracket will fit the 2.5" wood. Mounting holes (which attach with #14 hex head wood self-taping screws) of the bracket are about 2" on center which may be too close to end of wood...splitting wood on insertion.".... but anything can be modified or re-drilled to do what is necessary.

Necessity is STILL the mother of invention.

The only thing that I can add is ...give yourself some room to fit the strakes between your bunks. It is a constant problem and discussion here and on other sites about getting the bunks katty-whampus /diagonally/or off-center relative to the strakes.

Then, finding the amount of force that it takes.... to actually lift the whole boat and re-center.... is not a joyous event.

Another method of re-centering is to back the boat in and start all over.

I am old. I have added a power winch. After doing some rigging, I can clip the hook onto my boat and let the winch pull it up from the center all the while straightening the hull relative to the strakes and the bunks.

There are many ways to skin the cat.

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LDUBS
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by LDUBS » 19 Apr 2018, 15:02

Hmmm, had another thought building on Rich's comments. You could leave the existing 2"x4" bunk and put a 2"x2" or 2"x2.5" right on top of it. I've never seen it done this way but maybe it would work. Kind of like this:
bunk.png
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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 19 Apr 2018, 15:33

LDubs...I like it.

The only issue I can see is that you would be moving the boat HIGHER relative to its wheels. That can cause an issue on shallow ramps.

Yet, that could be combatted by lowering the supports. Most of them have lots of adjustment space available. Or, flip the axle over if the trailer allows it.

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Tin Man
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Tin Man » 20 Apr 2018, 09:16

I'm leaning towards the 2x2.5 on top of 2x4. Lowering bunks is not an issue as there is plenty of adjustment.

NOTE: Called an alum boat builder here in CA (similar to my boat) and he stated that due to the spacing between strakes (2.5") it really didn't matter if bunk boards were directly under strakes. The proximity of strakes added hull strength to bottom...also considering weight of hull is about 300#, if that.
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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 20 Apr 2018, 09:22

"The proximity of strakes added hull strength to bottom.."

I've always felt that strakes have two roles. One is to strengthen the thin aluminum sheeting, and the other is that the strakes provide some prevention from the hull sliding out in turns.

Years ago, I had a number of flat bottom fiberglass boats ( 3 were Carolina Skiffs). Sliding out in turns was a daily occurrence, unless you slowed way down or turned more gently.

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Tin Man
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by Tin Man » 20 Apr 2018, 09:44

So......does it really matter if bunks boards are directly under/partially under strakes?
Is the concern that any bouncing of boat could damage strakes?
Are there other concerns?
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thedude
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Re: Bunks on Alum boats with hull strakes -Where to place bu

Post by thedude » 20 Apr 2018, 10:39

Would think if you had bunks contacting two strakes would be fine. Contacting one would not be good.

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richg99
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Bunks on Alum boats with hull strakes -Where to place bunks?

Post by richg99 » 20 Apr 2018, 10:42

Every one that I have ever seen or used personally have been between the strakes.

Due to gravity, I think the boat will want to position itself between the strakes, no matter what you do.

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