Strut Question

[Sawtooth]

I am looking for opinions or even facts about which way to go would be better, drop through VS bottom mount for a strut in a 21' RC. Does one have more strength than the other, I would think the drag would be the same if the bottom mount deal was installed flush. Set up/install seems it would be a little more work with a drop through. Any info or thouhgts throw them out there.

 

[RiverDave]

Post this question in the v drive section. Stan is going out of town, but we have prime marine and Racey industries also checking in daily for tech questions such as this. .

RD

 

[Racey]

I personally believe that recessed struts with an internal strut brace are stronger than most drop thrus, the reason being that most drop thrus are only tapped into the glass, and have no nuts on the bolts, which means no clamping force on the hull... a strut brace between the stringers becomes a must for the drop thru style .

However i will say that the drop thru strut itself is stronger than a recessed strut because there is no weld joint to fail, and the web itself is supported through the hull....

The ideal situation in my opinion would be a drop through strut, but with the bottom of the hull still recessed where you could install stainless backing plates and flat heads up through the bottom which could either be nutted or tapped into the strut base on the inside of the boat....

 

[Sawtooth]

Hey Racey I like your idea, that sounds like the best of both worlds. Thanks for the reply. I am still in the planing stages but either way I go I will beef up the floor when I install the new stringers.

 

[BamBam]

My two cents. In a retrofit you would be much better off with a drop through. I don't understand Racey's comment on tapping the bolts into the fiberglass, Can't picture that. If you were to install a recessed/welded strut on your boat you would have to router out the bottom. The bottom on your boat is not nearly as thick as a boat laid up as a V-Drive originally. When they lay up a V-Drive for a recessed strut there is an insert in the mold so the fiberglass is laid around and over the void. The fiberglass you are cutting through is a mesh which gains it's strength as part of a membrain. When you cut that you will weaken it even if you add glass. This is an extremely high stress part of a V-Drive. You are going to need to add glass in this area no matter which way you go. Personally I would go with a drop through and tie it to the stringers. I did not tie mine to the stringers and I certainly will retro-fit that the next time the engine is out. I am glad to see the effort you are putting into this re-build.

 

[Sawtooth]

Thanks for your reply Bam Bam, yeah I am leaning toward the drop through strut. I was planing on beefing up the floor in the boat, in one of my conversations with Lee he also said it would be a good idea to stiffen up the floor with a couple layers of 1708 over the complete bottom so thats the plan. Thanks for the props on my project, I finely am able to take some time in two weeks and plan on finishing the grinding/sanding and going to try cutting/fitting the new stringers.:thumbsup

 

[Racey]

I don't understand Racey's comment on tapping the bolts into the fiberglass, Can't picture that.

On a drop-thru strut, the bolts that hold the strut to the bottom of the boat, they don't have nuts on the other end, obviously, because those nuts would be on the outside/bottom of the boat. The bolts are just tapped into the fiberglass. :thumbsup

 

[BamBam]

On a drop-thru strut, the bolts that hold the strut to the bottom of the boat, they don't have nuts on the other end, obviously, because those nuts would be on the outside/bottom of the boat. The bolts are just tapped into the fiberglass. :thumbsup

My drop through has flat heads through from the bottom flushed out and filled with nuts on the top. I could not imagine someone putting a strut in with bolts threaded into the glass with no nuts. Sounds scary to me. I have built a few and never would I consider putting a strut on with no nuts.

 

[ColeTR2]

I personally believe that recessed struts with an internal strut brace are stronger than most drop

I to like recessed struts for any boats the will be used for recreation. And even if i was building a full on 21' race boat, I'd still lean towards one. Just my .02