7mm vs Semi-dry

[Delano Diver]

Hi all,
I'm debating between a 7mm suit and a semi-dry. My question is basically this...if the water is cold enough to need a 7mm, should I just step up and get a semi-dry? I'm assuming a 7mm isn't that versatile anyway, in that I'm not going to be diving in both cold (<60) and warm water (>70-75) with it. In other words, if its cold enough for a 7mm, its cold enough for a semi-dry; and if its too warm for a semi-dry, its too warm for a 7mm. Am I correct, or way off mark?

Thanks for the help.

 

[Boogie711]

For what it's worth, I bought a Mares Isotherm. It's a wonderful suit. But if I had to do it over again, I wouldn't have. A new Mares Isotherm is like, $350 or so.

For that kind of money, I would have been better to get an entry level drysuit and been really warm, not faking it. Something like a Bare NexGen.

I kind of wish I had bought just a cheap 7mm - even something used from the rental department - to get me through a spring/summer/fall of diving, and saved my money for a drysuit. As it turns out, now I have a DUI that I use whenever it's chilly, and a Mares Isotherm that's going to sit in my closet 95% of the time.

 

[wreckchick]

ditto.

Rachel

 

[Bob3]

Your "semi-dry" is probably going to be 7mm thick anyway, the only difference will be some extra little gaskets inside the sleeves & legs to minimize water exchange.
The two will be interchangeable as far as water temps go, the "semi-dry" is just a little more efficient in eliminating the flushing action.
If you get one with an attached hood, it'll be a step up.

 

[DA Aquamaster]

I have a Scubamax 7mm semi-dry and find it works well in water from low 70's to low 40's. The seals are pretty simple and with a combination vest/hood there is minimal water flow through the neck. Cost of the Suit was around $180 2 years ago.

I also have a 7mm semi-dry that uses a back entry dry suit zipper and neoprene wrist and ankle seals. If it had a full blown neck seal it would in fact be a dry suit. It's warm even by semi-dry standards and will have spots in the suit that do not even get wet. The downside is that it is not self donning and this type of semi-dry is generally more expensive.

Fit is still very important with a semi-dry. The original idea with a semi-dry was that the seals would allow a less than perfect fit so that fewer sizes could be stocked and/ or mail order sales would be more feasible. The theory however has significant limitations as a loose spot under an arm will make an extremely powerful pump when you move and defeat the seals in the suit. So even the best semi-dry will not be warm if it does not fit reasonably well. And a very good fitting 7mm wet suit will normally be just as warm as a 7mm semi-dry. So in short, I would buy the one that fits the best and go with the semi-dry if the fit is equally good between the two.

With a 7mm wet or semi-dry, the hood you wear or don't wear can go a long way to controlling the temp. I use a 7mm hood with attached vest for cold water, a normal 7mm hood when it warms up some and a 3mm hood when to no hood at all when it gets toastier.

 

[TDunbar]

I agree with Bob. But I'd add that a well-fitting 7mm wetsuit may be just as warm as the semidry. If you can't find a good fit in a stock size wetsuit and aren't ready to move into a drysuit, the semidry makes sense. I bought a used Isotherm that was WAY too big, but I stayed alot warmer in it than anything I'd been in up to that point. When I bought a drysuit, I sold the Isotherm for what I paid for it.

 

[onfloat]

I have a question along the same lines. My LDS has suggested a semi-dry that has combinations of 8/7/6/5mm with an attached hood. It goes for $330.00. Water temps here are any where from 50 to 60 degrees. I was told that the dry suits start at about $1000.00. Where the heck is every one finding dry suits that are close to the semi-dry price (with in a couple of hundred or so)???

 

[Bob3]

Where the heck is every one finding dry suits that are close to the semi-dry price...???

You might try checking out the "gear for sale" forum: http://www.scubaboard.com/forumdisplay.php?f=101 wink

 

[caymancase]

Along this 7MM v semi dry... I'm planning a trip to cold water (well, cold for me). Not having much knowledge about having to wear more than 3 mm, can anyone let me know if you have more movement restriction in a 7mm over a semi dry? Or is that just a matter of which brand you buy.

 

[DA Aquamaster]

Along this 7MM v semi dry... I'm planning a trip to cold water (well, cold for me). Not having much knowledge about having to wear more than 3 mm, can anyone let me know if you have more movement restriction in a 7mm over a semi dry? Or is that just a matter of which brand you buy.

In a 7mm semi-dry or wet suit restriction is largely a function of fit. If it's too tight it will feel restrictive. The cut of the suit is also important and most suits today are well designed from an anthropomorphic standpoint. The old practice with wet suits used to be to use as few panels as possible to reduce seams, seam leaks and water flow. Combined with nylon, those suits were stiff and restrictive.

Current suits of both types will use additional panels to get better curves and will also often use a thinner material in the elbows and back of the knee area to improve flexibility.

So a good fitting 7mm suit is not too restrictive whether it be a wet suit or a semi dry. But in both cases a loose fitting suit will be a cold suit.

Where the heck is every one finding dry suits that are close to the semi-dry price (with in a couple of hundred or so)???

New neoprene dry suits are substantially cheaper than tri-laminate, vulcanized or compressed neoprene dry suits and can be found in the $500-$600 range.

E-bay is also an option if you know exactly what you want, what suit you are buying and what size you need. With a little (sometimes a lot) of patience, the perfect used dry suit will come along for under $300 and if you are less patient, finding one for under $500 is pretty easy.

ALso check the local dive shops they may have a solid used suit or a demo for sale or may know where to get one or know of someone trying to sell one. Demo suits in particular can be a very good deal.