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 Post subject: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 06:52 
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Rail Meat

Joined: 28 Sep 2015 23:39
Posts: 10
I've got someone working on my boat who's suggesting I need to increase the mast rake aft. He was looking at the base of the mast today and said that there are bolts at the step where the base of the mast might be tweaked fore and aft, and this might be an easier way of making the required adjustment. Does anyone have any experience with this? Is it possible to just loosen up those bolts, loosen the stays and bump the base of the mast forward?


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 11:58 
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Skipper

Joined: 13 Feb 2011 21:19
Posts: 337
Location: Canyon Lake, TX
First off, I don't have any experience with moving the mast base as a way to change the rake.

That said, those are screws on my 1980 model and not bolts. And on my boat, there is not a lot of forward displacement available. And how much sag do you have on your forestay? Because that sag is going away when you move the mast foot. All in all, I believe it's doable. But then again, I'm not a rigger.

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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 15:21 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 725
Location: Maine/USVI
Ease the headstay and crank on the backstay. If the mast is centered in your collar, I wouldn't move it around. Thinking about it, without looking, are those BOLTS with nuts backing or are they LAG BOLTS? I'm not sure I'd tinker with the mast step to increase rake. Just moving the column back wouldn't do it. Seems as though you'd move it forward, and then ease the headstay and crank on the backstay. But I don't see much rake in mine (I tried), but I didn't get under the furler to ease that headstay turnbuckle.


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 16:59 
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Rail Meat

Joined: 28 Sep 2015 23:39
Posts: 10
Attachment:
mast step screws.jpg

mast step screws.jpg [ 3.41 MB | Viewed 0 times ]



Thanks for the input. i’m not sure if they’re bolts or screws, and I’m not near the boat now so can’t post a photo of my own boat (1981 model), but I’ll attach a photo lifted from elsewhere in the forum of the step minus the mast. From this, yes, they look like screws rather than bolts. So I assume they can be used to adjust the mast’s position on the step. And, yes, I think the plan is to move the base of the mast forward a little, I suppose that this will pivot it slightly around the collar, and then make appropriate adjustments on fore and back stay.
WayneH, there’s no sag on the forestay. The shipwright says he will need to fit a longer connection to get more play in the stay.


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 18:57 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
The rake is more a function of headstay length than mast base position. The amount of rake you want is dictated by balance of the helm. These boats carry a fair bit of weather helm. Much of that is desirable because the increased angle of attack on the rudder increases lift with the downside of increasing drag. Moving the base without changing forestay length really won't buy you much and in either case you will need to also adjust ALL of your shrouds and backstay to match. I've said before that these boats definitely benefit from an adjustable backstay because you are adjusting the rake when you adjust the backstay, but the big impact is headstay tension that has a large effect on genoa shape.

BTW, I notice that your grounding wire and base is heavily corroded. Consider cleaning it off to reduce resistance from near lightning strikes or replace the whole system like I did with proper cable.


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 24 Mar 2021 21:43 
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Rail Meat

Joined: 28 Sep 2015 23:39
Posts: 10
Thanks Jfalsone. If I get you correctly, because T37 carry a fair bit of weather helm, you don't need as back rake in the mast as other boats? The shipwright suggesting the work (who, I might add, has been doing it for 50 years, and I've barely started sailing) is taking it from sight rather than how the boat is handling. Another issue is the boat seems unbalanced fore and aft—the stern is sitting very high out of the water—and Im not sure how the two (mast+high stern) might be interacting...
(by the way: the photo of the mast step, that you mention being corroded is not taken from my boat, but is just a photo I've lifted from elsewhere in the forum to point out the adjustment screws.)


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 25 Mar 2021 07:33 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
Mast step position won't significantly alter trim. I would be more concerned with keeping the mast centered in the partner. As for your trim issue, either you have a very heavy bow (gear?) Or a very light stern (lighter engine, empty fuel tank? No gear?). Other than some port list with full fuel and empty starboard water tank, these boats seem to sit on their lines just fine. If you have water collecting in the front of your cockpit you are bow down.


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 25 Mar 2021 13:48 
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Tactictian

Joined: 16 Jan 2019 08:52
Posts: 103
I have seen in this forum somewhere (2007). considerable information on the rake of the mast and the fact that 5/6" is attainable by adding to the forestay length and taking up more on the backstay. There is also discussion about the joined sections being quite heavy and not really flexing much. Mark #337

viewtopic.php?p=692


 
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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 26 Mar 2021 15:48 
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Skipper

Joined: 14 Jul 2012 20:36
Posts: 495
Location: Norfolk, Va
The T37 will trim down once you add a couple people in the cockpit. 400 lbs will drop the waterline about an inch. It actually brings the rake aft with that. The T37 does sit with a mast forward and has the look, without live ballast. I actually went forward (more straight) mast rake. The weather helm on T37 is pretty big factor. We do beer can races and if you race you are more likely to be overpowered than if you're cruising and it helps in keeping the boat balanced. Racers set sails for lulls, cruisers set for the puffs. A rake mast does look fast in the slip and my Hobie 33, I had the mast rake all the way back. I think the T37 sails better with it forward. If you do move the rake aft make it so its reversible by adding a toggle or two. Don't be afraid to play with it. I've moved mine a couple times over 26 years and we sail pretty well. The raked mast does have a better helm or feel in lighter air like 7-10kts. Just my two cents.

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 Post subject: Re: fore and aft adjustment of the mast at the step?
PostPosted: 29 Mar 2021 06:22 
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Rail Meat

Joined: 28 Sep 2015 23:39
Posts: 10
Wow! it must be something to do with the exchange rate. That two cents worth might just have saved me hundreds of dollars down here in Australia Puffcard Very Happy


 
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